How to reproduce:
1. Open user-submitted project (DoubleMemoryMesh.zip), SampleScene
2. Make a development build with the 'joker_thief_RW' in the scene
3. In the scene replace 'joker_thief_RW' with 'joker_thief' and make another development build
4. Open each build, attach Unity profiler and take a detailed memory sample
5. Compare the memory report of Assets/Mesh for both builds

Expected result: model with Read/Write enabled reports memory consumption correctly
Actual result: model with Read/Write enabled either reports identical memory consumption as without R/W or only a slight increase(~0.2MB)

Reproducible with: 2018.4.26f1, 2019.4.8f1, 2020.1.3f1, 2020.2.0a21

Notes:
Tested on macOS
Newest versions of Unity report higher memory consumption for R/W models, but only marginally(0.2 MB difference); may still be incorrect
2018.4.26f1 - Read/Write disabled: 2.2 MB
2018.4.26f1 - Read/Write enabled: 2.2 MB

2019.4.9f1 - Read/Write disabled: 1.8 MB
2019.4.9f1 - Read/Write enabled: 2.0 MB

2020.1.3f1 - Read/Write disabled: 1.8 MB
2020.1.3f1 - Read/Write enabled: 2.0 MB

2020.2.0a21 - Read/Write disabled: 1.8 MB
2020.2.0a21 - Read/Write enabled: 2.0 MB