How to reproduce:

1. Open attached project
2. Open scene Scene 1/scene1.unity
3. Open the Profiler window, switch to Memory tab
4. Play the scene
- Make note of the total memory used
5. Stop playing the scene
6. Select any sprite in the scene
7. Change its Sprite to an HD version
- SD and HD sprites have the same names, so can be easily changed using the Quick select box
8. Select any other sprite that uses a different Sprite and repeat step 7
9. Play the scene again
- Note how the total memory used has increased by some arbitrary amount
10. Stop playing the scene
11. Repeat from step 6, except changing the sprites back to the SD version
- Note how the total memory used has again increased by some arbitrary amount
- This happens each time the sprites are changed back and forth in this way