It's a household term for any Evil Dead/Sam Raimi/Bruce Campbell fan for sure! 1979's The Evil Dead was the first picture to employ the term "Fake Shemps" in the credits-- puzzling for viewerws not "in the know" as far a Stooge lore goes but, certainly, worth a snicker for anyone who, at least, recognised the name Shemp. For Raimi and company, though, the term goes back even further to their experimental, Super-8 movie making days.
If you can take anything Bruce Campbell says seriously, it would seem that he and his contemporaries enjoyed the living hell out of spotting the "fake" Shemp (Joe Palma) while watching those all too familiar 2-reelers on television. The branding stuck with Bruce and Raimi, both heavily influenced by the antics of the boys. They even went so far as to remake (along with another up-and-coming filmmaker Josh Becker) some of the Stooges' shorts entirely as Super-8 condensed versions (yes, some are online and they are very, very strange to say the least!). Additionally, Stooge gags were used in all 3 of the Evil Dead films with some of that influence trickling into the blockbuster Spider-Man franchise.
Or, if you just want the easy answer: Yup.