How to reproduce:

1. Open the attached "InputSystemBug.zip" Unity project
2. Open and play the "SampleScene"
3. Click on the “Add Keyboard/Mouse Player button”
4. Click on the “Add Gamepad Player“ button twice
5. Click on the “Add Virtual Cursor to Player 1“ button
6. Click on the “Add Virtual Cursor to Player 2“ button
7. Click on the “Add Virtual Cursor to Player 0“ button
8. Go to “Window > Analysis > Input Debugger”
9. Expand “Users > User #0/#1/#2 > Paired Devices" for each one of the three Users and observe the results

Actual Result(Screenshot attached):
Player 0 - paired with “Gamepad”, “VirtualMouse1”, “VirtualMouse2”
Player 1 - paired with “Gamepad1”, “Mouse1“
Player 2 - paired with “Keyboard1“, “VirtualMouse“

Expected Result:
Player 0 - paired with “Keyboard1“, “Mouse1“, “VirtualMouse“
Player 1 - paired with “Gamepad“, “VirtualMouse1“
Player 2 - paired with “Gamepad1“, “VirtualMouse2“

Reproducible in: 1.14.2(6000.0.61f1), 1.18.0(6000.5.0a7)
Could not test with: 6000.0.0b11 and older input system versions (input system breaks on them (many "The type or namespace name does not exist in the namespace", "The non-generic type..." and other errors))

Reproducible on: MacOS 26.2 (M1)
Not reproducible on: No other environment tested

Note:
- More information about this issue in our Unity Discussions: [https://discussions.unity.com/t/inputuser-performpairingwithdevice-changes-all-users-devices-in-specific-instances/1697902]