Generally I can't say I have this problem. Very occasionally I get an issue (double recording, missed episode, etc), but it doesn't happen often.
Admittedly I'm using Sky Q rather than Sky+, but it uses the same EPG
data so it should work the same.
Usually when this happens it's down to an error at the broadcaster's end rather than it being an issue with the software on the box. Every 'series' is assigned a unique series link number, and the box searches for this to find the next episode to record. If the broadcaster is putting the same number on all the repeats, the box will think they're all new episodes that need to be recorded.
It'll be worth checking if recordings from other channels have the same issue, as I suspect this is what's going on.