diff --git a/Clava-JS/src-api/clava/code/StatementDecomposer.test.ts b/Clava-JS/src-api/clava/code/StatementDecomposer.test.ts
new file mode 100644
index 000000000..70db2444e
--- /dev/null
+++ b/Clava-JS/src-api/clava/code/StatementDecomposer.test.ts
@@ -0,0 +1,79 @@
+import { registerSourceCode } from "@specs-feup/lara/jest/jestHelpers.js";
+import Query from "@specs-feup/lara/api/weaver/Query.js";
+import { FunctionJp, Vardecl } from "../../Joinpoints.js";
+import NormalizeToSubset from "../opt/NormalizeToSubset.js";
+
+const codeWithExistingDecompVars = `
+int foo(int a) {
+  int decomp_0 = 5;
+  int decomp_1 = 10;
+  int result = (a + 1) * (decomp_0 + decomp_1);
+  return result;
+}`;
+
+describe("StatementDecomposer duplicate symbols", () => {
+  registerSourceCode(codeWithExistingDecompVars);
+
+  it("should not create duplicate decomp_ symbols when normalizing", () => {
+    const functionJp = Query.search(FunctionJp, { name: "foo" }).first();
+    
+    if (functionJp === undefined) {
+      fail("Function not found");
+    }
+
+    // Get all variable names before normalization
+    const varsBefore = Query.searchFrom(functionJp, Vardecl).map(v => v.name);
+    expect(varsBefore).toContain("decomp_0");
+    expect(varsBefore).toContain("decomp_1");
+
+    // Apply normalization
+    NormalizeToSubset(functionJp);
+
+    // Get all variable names after normalization
+    const varsAfter = Query.searchFrom(functionJp, Vardecl).map(v => v.name);
+    
+    // Check that all variable names are unique
+    const uniqueVars = new Set(varsAfter);
+    expect(uniqueVars.size).toBe(varsAfter.length);
+    
+    // Ensure no duplicate decomp_0 or decomp_1
+    const decompCounts: Record<string, number> = {};
+    for (const varName of varsAfter) {
+      if (varName.startsWith("decomp_")) {
+        decompCounts[varName] = (decompCounts[varName] || 0) + 1;
+      }
+    }
+    
+    for (const [varName, count] of Object.entries(decompCounts)) {
+      expect(count).toBe(1);
+    }
+  });
+});
+
+const codeMultipleNormalization = `
+int bar(int x) {
+  return (x + 1) * (x + 2);
+}`;
+
+describe("StatementDecomposer multiple normalizations", () => {
+  registerSourceCode(codeMultipleNormalization);
+
+  it("should not create duplicate symbols when normalizing multiple times", () => {
+    const functionJp = Query.search(FunctionJp, { name: "bar" }).first();
+    
+    if (functionJp === undefined) {
+      fail("Function not found");
+    }
+
+    // Apply normalization twice
+    NormalizeToSubset(functionJp);
+    NormalizeToSubset(functionJp);
+
+    // Get all variable names
+    const vars = Query.searchFrom(functionJp, Vardecl).map(v => v.name);
+    
+    // Check that all variable names are unique
+    const uniqueVars = new Set(vars);
+    expect(uniqueVars.size).toBe(vars.length);
+  });
+});
diff --git a/Clava-JS/src-api/clava/code/StatementDecomposer.ts b/Clava-JS/src-api/clava/code/StatementDecomposer.ts
index ffba11fbb..d0240dfbb 100644
--- a/Clava-JS/src-api/clava/code/StatementDecomposer.ts
+++ b/Clava-JS/src-api/clava/code/StatementDecomposer.ts
@@ -1,16 +1,20 @@
 import { debug } from "@specs-feup/lara/api/lara/core/LaraCore.js";
+import IdGenerator from "@specs-feup/lara/api/lara/util/IdGenerator.js";
+import Query from "@specs-feup/lara/api/weaver/Query.js";
 import {
   BinaryOp,
   Call,
   Case,
-  Decl,
+  type Decl,
   DeclStmt,
   EmptyStmt,
   ExprStmt,
-  Expression,
-  Joinpoint,
+  type Expression,
+  FunctionJp,
+  type Joinpoint,
   LabelStmt,
   MemberCall,
+  type Param,
   ReturnStmt,
   Scope,
   Statement,
@@ -25,17 +29,81 @@ import DecomposeResult from "./DecomposeResult.js";
  * Decomposes complex statements into several simpler ones.
  */
 export default class StatementDecomposer {
-  tempPrefix;
-  startIndex;
+  public tempPrefix;
+  public startIndex;
+  public useGlobalIds;
+  private symbolTable: Set<string> | undefined;
+  private currentFunction: FunctionJp | undefined;
 
-  constructor(tempPrefix: string = "decomp_", startIndex: number = 0) {
+  /**
+   * Creates a new StatementDecomposer.
+   * 
+   * @param tempPrefix - Prefix for temporary variable names
+   * @param startIndex - Starting index for temporary variable names (ignored if useGlobalIds is true)
+   * @param useGlobalIds - If true, uses global IdGenerator to avoid duplicate symbols across multiple normalizations
+   */
+  public constructor(tempPrefix = "decomp_", startIndex = 0, useGlobalIds = false) {
     this.tempPrefix = tempPrefix;
     this.startIndex = startIndex;
+    this.useGlobalIds = useGlobalIds;
+  }
+
+  /**
+   * Builds a symbol table of existing variable declarations and parameters in the given scope.
+   * This is used to avoid creating duplicate variable names.
+   * 
+   * @param $scope - The scope to build the symbol table from (typically a function)
+   */
+  private buildSymbolTable($scope: Joinpoint): void {
+    // Get the enclosing function if we're not already at a function
+    const $function = $scope instanceof FunctionJp 
+      ? $scope 
+      : $scope.getAncestor("function") as FunctionJp | undefined;
+    
+    // If we're in the same function as before, reuse the symbol table
+    if ($function === this.currentFunction && this.symbolTable !== undefined) {
+      return;
+    }
+    
+    // Reset for new function
+    this.currentFunction = $function;
+    this.symbolTable = new Set<string>();
+    
+    if ($function === undefined) {
+      return;
+    }
+    
+    // Add parameter names to symbol table
+    for (const $param of $function.params as Param[]) {
+      this.symbolTable.add($param.name);
+    }
+    
+    // Add all variable declarations in the function to symbol table
+    for (const $vardecl of Query.searchFrom($function, Vardecl)) {
+      this.symbolTable.add($vardecl.name);
+    }
   }
 
   private newTempVarname() {
-    const varName = `${this.tempPrefix}${this.startIndex}`;
+    if (this.useGlobalIds) {
+      // Use global IdGenerator to ensure unique names across multiple normalizations
+      return IdGenerator.next(this.tempPrefix);
+    }
+    
+    // Use local counter with symbol table checking to avoid duplicates
+    let varName = `${this.tempPrefix}${this.startIndex}`;
     this.startIndex++;
+    
+    // If we have a symbol table, ensure the name is unique
+    if (this.symbolTable !== undefined) {
+      while (this.symbolTable.has(varName)) {
+        varName = `${this.tempPrefix}${this.startIndex}`;
+        this.startIndex++;
+      }
+      // Add the new name to the symbol table
+      this.symbolTable.add(varName);
+    }
+    
     return varName;
   }
 
@@ -94,6 +162,9 @@ export default class StatementDecomposer {
    * @returns An array with the new statements, or an empty array if no decomposition could be made
    */
   decompose($stmt: Statement): Statement[] {
+    // Build/refresh symbol table for the current function to avoid duplicate variable names
+    this.buildSymbolTable($stmt);
+    
     try {
       return this.decomposeStmt($stmt);
     } catch (e) {
diff --git a/Clava-JS/src-api/clava/opt/NormalizeToSubset.example.md b/Clava-JS/src-api/clava/opt/NormalizeToSubset.example.md
new file mode 100644
index 000000000..13d2b9f78
--- /dev/null
+++ b/Clava-JS/src-api/clava/opt/NormalizeToSubset.example.md
@@ -0,0 +1,67 @@
+# NormalizeToSubset Usage Examples
+
+## Basic Usage
+
+```typescript
+import NormalizeToSubset from "./NormalizeToSubset.js";
+import Query from "@specs-feup/lara/api/weaver/Query.js";
+
+// Apply normalization to the entire program
+NormalizeToSubset(Query.root());
+```
+
+## With Options
+
+### Using Global IDs (Recommended for Multiple Normalizations)
+
+When you need to apply normalization multiple times over the same AST region, use the `useGlobalIds` option to prevent duplicate symbol generation:
+
+```typescript
+import NormalizeToSubset from "./NormalizeToSubset.js";
+import Query from "@specs-feup/lara/api/weaver/Query.js";
+import { FunctionJp } from "../../Joinpoints.js";
+
+const functionJp = Query.search(FunctionJp, { name: "myFunction" }).first();
+
+// Apply normalization with global ID generation
+NormalizeToSubset(functionJp, { useGlobalIds: true });
+
+// Safe to apply again - will not create duplicate symbols
+NormalizeToSubset(functionJp, { useGlobalIds: true });
+```
+
+### Custom Loop Simplification
+
+```typescript
+import NormalizeToSubset from "./NormalizeToSubset.js";
+import Query from "@specs-feup/lara/api/weaver/Query.js";
+
+// Customize loop simplification behavior
+NormalizeToSubset(Query.root(), {
+  simplifyLoops: { forToWhile: false },
+  useGlobalIds: true
+});
+```
+
+## Symbol Table Management
+
+The StatementDecomposer automatically builds a symbol table of existing variable declarations and parameters before generating new variable names. This prevents conflicts with existing `decomp_N` variables in your code.
+
+### Example
+
+Given this code:
+```c
+int foo(int a) {
+  int decomp_0 = 5;  // Existing variable
+  int result = (a + 1) * (2 + 3);
+  return result;
+}
+```
+
+When normalized, the transformation will create `decomp_1`, `decomp_2`, etc., skipping `decomp_0` to avoid conflicts.
+
+## Implementation Details
+
+- **Symbol Table**: Collects all parameter and variable declaration names from the enclosing function
+- **Local Counter**: By default, uses a local counter that checks against the symbol table
+- **Global ID Generator**: When `useGlobalIds: true`, uses `IdGenerator.next("decomp_")` for globally unique names across the entire transformation session
diff --git a/Clava-JS/src-api/clava/opt/NormalizeToSubset.ts b/Clava-JS/src-api/clava/opt/NormalizeToSubset.ts
index 9d190a9ad..e597c74f7 100644
--- a/Clava-JS/src-api/clava/opt/NormalizeToSubset.ts
+++ b/Clava-JS/src-api/clava/opt/NormalizeToSubset.ts
@@ -1,6 +1,6 @@
-import { LaraJoinPoint } from "@specs-feup/lara/api/LaraJoinPoint.js";
 import Query from "@specs-feup/lara/api/weaver/Query.js";
-import { BinaryOp, Joinpoint } from "../../Joinpoints.js";
+import type { Joinpoint } from "../../Joinpoints.js";
+import { BinaryOp } from "../../Joinpoints.js";
 import SimplifyAssignment from "../code/SimplifyAssignment.js";
 import StatementDecomposer from "../code/StatementDecomposer.js";
 import DecomposeDeclStmt from "../pass/DecomposeDeclStmt.js";
@@ -11,22 +11,31 @@ import SimplifyReturnStmts from "../pass/SimplifyReturnStmts.js";
 import SimplifySelectionStmts from "../pass/SimplifySelectionStmts.js";
 
 /**
- *
- * @param $startJp -
- * @param options - Object with options. See default value for supported options.
+ * Normalizes code to a simpler subset of C/C++.
+ * 
+ * @param $startJp - Starting join point for normalization
+ * @param options - Configuration options for normalization
  */
 export default function NormalizeToSubset(
   $startJp: Joinpoint,
-  options = { simplifyLoops: { forToWhile: true } }
+  options: { simplifyLoops?: { forToWhile: boolean }, useGlobalIds?: boolean } = {}
 ) {
-  const _options = options;
+  const _options = {
+    simplifyLoops: { forToWhile: true },
+    useGlobalIds: false,
+    ...options
+  };
 
   const declStmt = new DecomposeDeclStmt();
   const varDecls = new DecomposeVarDeclarations();
-  const statementDecomposer = new StatementDecomposer();
+  const statementDecomposer = new StatementDecomposer(
+    "decomp_", 
+    0, 
+    _options.useGlobalIds
+  );
   const simplifyLoops = new SimplifyLoops(
     statementDecomposer,
-    _options["simplifyLoops"]
+    _options.simplifyLoops
   );
   const simplifyIfs = new SimplifySelectionStmts(statementDecomposer);
   const simplifyReturns = new SimplifyReturnStmts(statementDecomposer);