How to reproduce:
1. Open user-submitted project (Input_System)
2. Navigate to Edit > Project Settings > Input System Package
3. Click the + symbol to add a new device to the list of Supported Devices
4. See that 'Mouse' can be found in the root level of the list and under the 'Pointer' category
5. Search the devices for "Mouse"

Expected result: the duplicate 'Mouse' entry is omitted from the search
Actual result: the duplicate 'Mouse' entry is displayed in the search

Reproducible with: 2019.1.8f1, 2019.2.0b8, 2019.3.0a8
Could not test with: 2017.4.29f1(Package not yet implemented), 2018.4.3f1(Regressed package version not available)

Reproducible with package versions: 0.2.8, 0.2.10
Not reproducible with package versions: 0.2.1, 0.2.6
Could not test with package versions: 0.1.2, 0.2.0(Incompatibility issues)