Rip off is a term I'm increasingly getting tired of, as it's almost always misused.
First, because it ignores the role of inspiration in the creation of new things. For some weird reason, we increasingly demand new things be new to the point of being ex nihilo, that isn't the way things works. All new things come from something else, just as you inherit qualities from your parents, yet are a different and new from both.
The second issue is we also somehow think only one person can think something up when that's clearly not the case as the internet so loves to demonstrate.
JMS only realized he'd recreated A Canticle for Leibowitz after finishing writing A Deconstruction of Falling Stars, but he kept it as is because thinking it over he realized he was not deliberately trying to rip off that story.
His episode was not a rip off and the best that could be said was him being unconsciously inspired by Leibowitz. He kept things in place, yet did not leave them as is, as he worked through his world-building reasons as to why things would be the case in universe that made sense, the same sense that ultimately lay behind the very idea of post-apocalypse monks trying to rebuild civilization, the important thing was he worked to make it his own unique variant of the idea.
All work operates in the same way, whether we like it or not. It's why I find Harlan Ellison's reaction to Terminator so bloody annoying. Instead of seeing a new, young director producing a work clearly inspired by his Outer Limit episodes and being flattered and honoured to have influenced James Cameron, he bristled at the familiar in the movie took it for stealing and sued over it.
The thing about any rip off is that it very much walks like a duck and talks like a duck. One just has to glance at it for it to become apparent that the only original thought put into the work was to rip off something else:
