Email I got to send just now (details redacted):

Hello, excellent Department of Elections people!
I live at [address] [apartment number]. A few days back, I received my ballot (yay) and also the ballot for [someone else] [different address] (whoops) [same apartment number].
I put [her] ballot in a mailbox. When I checked my mail this morning, [her] ballot was there again, d'oh.
If it was once, I'd figure "accidents happen." Twice makes me wonder: uh, is some garbled scan code confusing some USPS autosorter or something i dunno
Anyhow, I'm gonna try writing a note to our postal carrier in hopes of getting this ballot delivered to the correct building. I'm attaching a snapshot of the envelope in case y'all want to look it over for things that might confuse a mail sorter.
-Larry H.

In tangentially-related news, it turns out that Louis DeJoy is no longer the head of USPS and hasn't been for some time. I'd grown comfortably accustomed to blaming him for all USPS failures, but apparently I should be shaking my head at David P. Steiner nowadays.