PowerToys Key Remapper New Editor cannot create certain remaps

### Microsoft PowerToys version

0.99.1

### Installation method

GitHub

### Area(s) with issue?

Keyboard Manager

### Steps to reproduce

1. Switch to the new editor
2. Add the following remap first: Alt(L) to Win(L), Win(L) to Alt(L)
3. Attempt to add one more remap: Alt(R) to Win(R)

### ✔️ Expected Behavior

Remap successfully set

### ❌ Actual Behavior

Error Appears, and cannot set the remap

### Upload Bug Report ZIP-file

_No response_

### Additional Information

The same remap can be set in the classic editor as shown in the last entry:

### Other Software

_No response_

Start in the Keyboard Manager new editor and reproduce the listed sequence: add the two left-side modifier remaps, then attempt the right-side Alt-to-Win remap. Compare the result with the classic editor; the issue is resolved when the third remap can be added successfully without the error.

Written by the indexing model from the issue text.