Hi – I was able to replicate the error you describe in the step copy procedure and solved it in the latest version of the source by not copying the hyper status of the source step to the target step.
One could argue that the hyper status should be taken over by the target and removed from the source, but regardless, a consistency check needs to be in place, so much is sure.
In terms of allowing more than one hyperstep to a track, that would involve a major change to the internal structures, is therefore not feasible in the short term.
Cheers,
Gabriel