@feditips
40 posts is too little, because I can get that in less than 10 minutes. And then the duplicates show up.
The problem is not simple. It is not just a matter of adjusting a knob. It will put more cpu load and memory pressure on server side to track duplicates.
It may be helpful to have a user setting that says do not show me boosts of a post where the timestamp of the original post is over 24 hours old.
Or 3 days, or 7 days. Let the user decide depending upon how often they read.
That is a usable knob that will not stress the instance, and save bandwidth.
Another idea: Have a button to flag that you saw it.
The software has no clue whether you actually read it or not.
The combination of the post age and the user flagging they read it will work wonders.