When I first joined, everyone was discouraging reposts because it could lead to duplicates of the same note in your follower's feed if they were already following the author of the note you reposted.
Discussion
Personally, I think it's great if we get duplicates in the feed. It mimics real speech, where good/important stuff also spreads when several people start talking to you about the same stuff. Can't be more organic, imo. This way, I'll also be much more likely to see it, instead of missing it in my feed.
One concern though is if the stuff being reposted is meant to be a distraction instead of good/important, it could potentially "flood the zone" and prevent important stuff from surfacing.
I guess most people only repost stuff that has high value to them. So imo unlikely that everyone reposts everything. If you have certain people you follow that start reposting stuff you don't like it all, unfollow would be the way. Just like in real life the neighbor etc. who always wants to chit chat about gossip you try to go out hus way or if not possible at some point you will tell him that you don't care about his gossip = mute him.