Interesting. I went back and replayed both of those levels. I believe this Jan 18 test level would have been great on its own without being too duplicative with those other two. This one and "Unless" both involved strategic welds, but otherwise felt quite different. And similar to this one, "Backtrack" required some careful traversing of gravity blocks, but again didn't seem duplicative.
Admittedly, this Jan 18 is the only test level I've tried so far so maybe the same could be said for many others, in which case understandably you can't keep everything! Maybe in a future release...
Thanks for your response.