I've only heard of it as,"kitbashing",or "kitbashed". This is taking parts from either one,or more models. This is done to save time for movie studios. Kitbashed refers to using only a few parts and not the entire model built as it should be. Some models are used for the design because their parts look like something that would be on a spaceship,or because they look "cool" with an interesting design.
This way you don't need to recast,unless you're using the same part over and over. The problem with this is,many model builders use the original kits to be more authentic to the original screen used prop without recasting these parts,as they're only using them for one build. The lineage of the models dwindles as time goes on because many of these kits are no longer made and are being used for single builds. ILM used the exact same kits for almost all their builds,so they used more than one kit,being that casting was still widely unused at that time for budget constraints. That and,recasting was still new technology in the seventies.
Now that we have smooth cast and other companies,we can preserve the lineage of these models. Sadly,there are still modelers that don't recast these parts and use them without a second thought! I can understand if they recast the parts,then used the originals,but they don't.