Best way to have such app enhancement/bug related discussions is to move such conversations to Github, e.g. File duplication error · Issue #5599 · nextcloud/android · GitHub
In case it was rather a general question if this is possible today
Is it possible to set “Overwrite files everytime” in “Automatic Backup Settings” in Android app?
It is not, which is why I mentioned github.
Hope this helps a bit 