Out of interest I just followed the following steps in the First Posts review queue:
- Visited the page to load an answer for review
- Up-voted the answer
- Opened the full URL to the question in a new tab
- Clicked 'I'm done' in the review queue
- Refreshed the full question page in the other tab, and removed my up-vote.
When I checked the review history for First Posts my review was (unsurprisingly) still there.
As I understand it the number of First Post reviews a user is allowed to carry in a day is directly linked to the number of votes they have remaining that day.
With that in mind, wouldn't it be quite easy for a user to follow the above process in an effort to earn badges more easily and 'cheat' the daily limit? Or are there other checks in place?