Been using Shotcut for a few years now a now and have never seen this behavior. When I click the split at playhead icon it makes the split but then duplicates the video immediately preceding the split. It happens with every playhead cut so it is actually impossible to edit.
I am not seeing that. It is not normal behavior. What is your version and OS?
And how are you spliiting: toolbar button, keyboard shortcut, or menu?
Linux. Shotcut version 25.11.2 tarball. I was splitting it using the standard split at playhead tool above the timeline.
I was able to work around it by converting the source into mkv lossless.
Duplicates the entire video clip by adding a new clip? Or duplicates the preceding frame? If it’s just a frame or two, then perhaps there is a seek precision problem with the source video.