I've gotten pegged by people when I reposted something I knew very well, hadn't been posted within a year's timeframe. Like, what's the problem with that? It hasn't been seen in so long so yeah it'll be reposted.
Unlike with your second scenario, I've seen posts crop up within the same day and they're all gratified and praised like as if people hadn't seen them before when their short attention spans fail to tell them that they did see it before very recently.
Could've been different people. This happened all the time with me seeing something for the first time in my life, while comments were full of complaints of it being reposted once a week.
Karma-whoring is especially bad when it’s just all bots doing it. There were many instances where even comments on karma posts were bot generated. Upvotes were much likely bot generated too.