[edanm]

But then my music files, which I edit the id-tags for, will show up as different than other people's when hashing.

It would be interesting for Dropbox to release numbers on how many music files are identical between different people.

[scottbessler]

I believe they could (and probably do?) de-dupe at a lower than file level to handle this issue.

[wlievens]

Good point. The ID3 tag is probably only in the header anyway. They'll just do it at a block level.