Reproduction steps:
1. Open the attached project ("case_1252144-AddressableAsync.zip")
2. Open the repro scene ("SampleScene")
3. Build Player Content
4. Set Play Mode Script to "Use Existing Build"
5. Enter Play Mode
6. Click the "Release Asset1" button in the scene
7. If no errors are thrown, exit Play Mode and repeat steps 5,6 again

Expected result: No errors are thrown and both assets are loaded
Actual result: "Cannot increment reference count" exception is thrown and only one asset is loaded

Reproducible with: 2020.1.0b8, 2020.1.0b11, 2020.2.0a7, 2020.2.0a13
Not reproducible with: 2018.4.23f1, 2019.4.0f1, 2020.1.0b7, 2020.2.0a5
Reproducible with package versions: 1.3.3, 1.9.2 (with 2020.1, 2020.2 stream only)
Not reproducible package versions: 1.1.5, 1.2.4