[Issue]: Two 8BitDo controllers (Client) detected as single controller (Host)

[Pandapancace]

Describe the bug

Bug Description

When connecting both an 8BitDo Ultimate C Bluetooth and an 8BitDo Ultimate 2C Bluetooth simultaneously via Bluetooth, Artemis only recognizes them as a single controller instead of two separate devices. Both controllers appear as a (Switch) Pro Controller

Expected Behavior

Both controllers should be detected and registered as two independent gamepads, allowing two-player input.

Actual Behavior

Only one controller is recognized regardless of which physical device is used. Input from both controllers appears to be merged or one controller is silently ignored.

Root Cause (suspected)

The two controllers likely report identical USB/Bluetooth vendor ID, product ID, or device descriptor strings, causing Android's input system (or Artemis's controller mapping layer) to treat them as the same device. This is a known issue class with 8BitDo controllers sharing hardware identifiers across product lines.

A potential fix could involve differentiating controllers by their Bluetooth MAC address in addition to their descriptor, similar to the approach used for distinguishing identical HID devices.

Environment

• App: Artemis (moonlight-android fork)
• Host: Apollo
• Device: Android tv (beamer)
• Controller 1: 8BitDo Ultimate C Bluetooth (Displayed as a Switch Pro Controller)
• Controller 2: 8BitDo Ultimate 2C Bluetooth (Displayed as a Switch Pro Controller)
• Connection: Bluetooth

Additional Context

This issue is not present when using two controllers of different brands or types (like one Xbox and one sswitch type controller on the client) , confirming the problem is descriptor-collision specific.

Steps to reproduce

1. Pair the 8BitDo Ultimate C Bluetooth (Switch Pro Controller) with the Android device
2. Pair the 8BitDo Ultimate 2C Bluetooth (Switch Pro Controller) with the same Android device
3. Launch Artemis and start a streaming session
4. Observe that only one controller is visible to the host

Affected games

All (Steam Input API, Lego Star wars: The skywalker Saga (Epic games) etc.)

Other Moonlight clients

None

Moonlight adjusted settings

None

Moonlight adjusted settings (please complete the following information)

No response

Moonlight default settings

Yes

Gamepad-related connection issue

No

Gamepad-related input issue

Yes

Gamepad-related streaming issue

Yes

Android version

Android TV 14

Device model

wanbo x5 pro projector

Server PC OS version

Windows 11 Pro

Server PC GeForce Experience version

Apollo 0.4.6

Server PC Nvidia GPU driver version

32.0.15.9649

Server PC antivirus and firewall software

Windows Defender and Firewall

Screenshots

No response

Relevant log output

Additional context

The two controllers are registered as Nintendo Switch controllers; both have a different Bluetotth adrees

[ClassicOldSong]

Have you tried with controller tester apps? How many controllers do you see in Artemis's debug info screen?

Generally I won't recommend 8bitdo products, they're hype over real value. Their USB stack has long hanging compatibility issues, it's just PC drivers and games are forgiving and game developing frameworks provide workarounds for them specifically so they can work.

[Pandapancace]

Thanks for the quick response!

After investigating further, here's what I found:

Controller tester apps on Android also only recognize one controller
It's not Artemis-specific. The root cause seems to be that Android identifies controllers by device class/type rather than by name or Bluetooth address. Since both the Ultimate C Bluetooth and Ultimate 2C Bluetooth are the same model/class, Android treats them as a single device and exposes only one input device to apps.

Artemis's debug screen shows only 1 controller, even with both physically connected and active.

For comparison: Moonlight on iPhone recognizes both controllers correctly as two separate gamepads. iOS apparently uses a different identification strategy (likely Bluetooth address), which is why it works there. Same controllers, same host, but the client platform differs.

The same issue also occurs in Amazon Luna on Android, which further confirms this is an Android-layer identification problem rather than something specific to Artemis.

A potential fix on the app side would be to use the Bluetooth address as a tiebreaker when two controllers share the same device class, similar to how the patch in moonlight-android's ControllerHandler.java addresses identical controller disambiguation. I understand if this is out of scope given 8BitDo's HID quirks — just wanted to give you the full picture.

[Pandapancace]

I did some more digging and looked into ControllerHandler.java to better understand what's going on.

The root cause seems to be at the Android OS level. Both Controllers report the same device descriptor over Bluetooth, so Android only exposes a single InputDevice for both physical controllers. By the time getAttachedControllerMask() iterates over InputDevice.getDeviceIds(), it only counts one device with joystick axes. Artemis never receives two separate InputDevice objects and therefore can't assign two different controller numbers.