diff --git a/src/hooks/use-preset-controls.js b/src/hooks/use-preset-controls.js
index 8c35b4b9c1..8bacdde9cb 100644
--- a/src/hooks/use-preset-controls.js
+++ b/src/hooks/use-preset-controls.js
@@ -72,7 +72,18 @@ export const usePresetControls = property => {
 	// This happens when settings like `typography.defaultFontSizes` or `spacing.defaultSpacingSizes`
 	// are not explicitly set to `false` in theme.json v3.
 	if ( hasThemePresets && wpDefaultPresets && defaultSizesEnabled !== false ) {
-		themePresets = [ ..._themePresets, ...wpDefaultPresets ]
+		// Create a set for removing duplicates.
+		const existingSlugs = new Set()
+		_themePresets.forEach( item => {
+			if ( item && typeof item.slug === 'string' ) {
+				existingSlugs.add( item.slug )
+			}
+		} )
+
+		themePresets = [
+			..._themePresets,
+			...wpDefaultPresets.filter( item => ! existingSlugs.has( item.slug ) ),
+		]
 	}
 
 	// Get the theme/default presets if the user have one, else return the stackable presets