[thaumaturgy]

I don't think cynicism is justifiable here. Let's use Occam's Razor:

1. Dropbox staff hand-crafted oddly-worded DMCA takedown notices and purposefully sent those to specific individuals after having already sent them polite requests to remove certain content;

2. Dropbox staff hand-crafted oddly-worded DMCA takedown notices at some point in the past as part of an automated system, which fired incorrectly when staff removed content.

To me, #2 makes a lot more sense, and is the simpler (and in this analysis, the more likely) case.

[Goronmon]

To be clear, Dropbox isn't wording any takedown notices. These are just automated e-mails saying that content is being removed because Dropbox itself received a takedown notice from a third-party and that they are complying.