How to reproduce:
1. Create a new project
2. Import the Memory Profiler from the Package Manager
3. Open the Memory Profiler window (Window -> Analysis -> Memory Profile)
4. Make a Snapshot by clicking the 'Capture Editor' button
5. Click the 'Import' button and select the newly taken Snapshot located in the MemoryCaptures folder

Expected result: the same Snapshot is not imported twice and a warning message occurs
Actual result: the same Snapshot is allowed to be imported

Reproducible with: 0.1.0-preview.1 (2018.4.26f1), 0.2.5-preview.1 (2019.4.9f1, 2020.1.3f1, 2020.2.0a21)

Notes:
When one of the imported Snapshots gets deleted from the list and the other one is opened, 'Could not find file' and 'NullReferenceException: Object reference not set to an instance of an object' exceptions get logged in the Console