Yeah, if you ask an explicitly dumb question you may get dumb answers…
When you copy and paste tracks and vias the operation keeps the nets if possible. If you paste them so that track endpoints are on some pads, KiCad tries to inherit new nets from the pads. Most probably you paste them so that the nets are not changed. Click on some of the pasted items and see what the net is.
The other replies are very rude (and from a moderator! bloody hell). IMO, this is a reasonable thing to do. I just did it in a layout of my own because I’m working in 8.0 which currently has no working “replicate layout” tool.
Generally if the nets do not remap when you duplicate them, it means there is a conflict somewhere – the two sections are not identical and your trace ended up touching more than one net, KiCad couldn’t decide which to connect it to so it left it as-is. In general, if you copy a trace to a new location it does get remapped exactly as you expect, though this behavior may have changed between versions - can you share more?
If you’re on 7.0 you should try the Replicate Layout plugin though, yes.
My comment can also be taken as hidden criticism towards Paul’s comment… I understand how Paul feels about it because it’s a bit difficult to take seriously a question (or person) which is told to be dumb even before asking it, especially in written form. On the other hand people who feel to be insecure about some field of knowledge and ask about something which they feel may be self evident for those who know a little bit more often express their insecurity. Including me sometimes. Maybe it works better in face to face discussion.
I used to be on a bargain hunting forum where people could post deals and offers they encountered. For some reason some newbies started prefacing their first posts with: Be nice to me this is my first post. This induced reactions ranging from mock cruelty, to other first posts starting: Go ahead beat me whip me I don’t care.
IMO such phrases used as introductions in face to face conversations are redundant on a forum. But I think responders should just skip past such stock phrases to keep the peace.