This has been tossed around inside and out between moderators, about how the flag dismissal system works when it comes to old flags. Prior to flag rating, bringing up the old flags helped for context and dismissal wouldn't really do anything. We made assumptions of how it worked in the new system. And, well, the Michaels were right, and I was wrong.
If a dismissed flag is "revived" from someone new flagging the same post, it can be redismissed and alter the flag weight of that user according to the new system. I noticed this after giving Gaming's Community a healthy +30 +40 bonus to its flag weight for a single post.
This can also result in someone's flag weight being cancelled because someone put a bogus flag on it at a later date.
Can an already-dismissed flag not affect the flag weight when it shows up again?