I am a moderator on Academia.SE. I just dismissed a comment flag that looked familiar. On closer inspection, I saw that I had previously dismissed that exact flag twice, and it had also been dismissed previously by two other moderators. All 5 flags were raised by the same user, who appears to have a pattern of raising multiple flags on comments. Nothing about the context of this particular comment changed during this period, i.e. there is no reason a user might think that a previously declined flag wasn't valid before, but is now.
To moderators, this behavior is problematic because we can't usually tell if a comment was flagged by several different users, or several times by the same user. It also wastes moderator time (I do not appreciate having to dismiss the same comment flag three times, from the same user).
What is the etiquette, in general, on re-raising comment flags that have been declined? Under what conditions should users re-raise comment flags?