Just tested on a Monomachine: same thing there. Copy pattern, select another pattern, try pasting before the step sequencer activates the other pattern. The other pattern settings will be recalled and you have to paste “again”…
In the OT you´re at least able to find a way to work around it, thanks to the samples and their lenght and loop settings. As per described in my post above. Not sure if and how one would be able to or how to do it, within the MD/MnM however…