I read the link, and it sounds like that answer is a total guess. The answerer has given no reason for his statement.
It could be based on checksum matching, which is what I'd do, or it *could* be based on Dropbox memorizing which computer last synced each file. Seems an awkward way of doing it.
I would prefer using my own data to answer this, what I recommend doing is using FreeFileSync to do a one-way mirror of the library, restore the partition with Dropbox and the mirror of the library, then see what happens.
For bonus points I would post an actual answer with actual facts on SuperUser.