I’m an oldster and never heard more than two standby’s. But maybe you’re misunderstanding things. We have multiple people here with actual 35mm film reels, and some of those film reels have been scanned (audio captured too) and made it into parts of the Despecialized Editions. Yes, home video isn’t always the same as the films upon which they’re based, etc, etc, but this sort of thing is settled. We have pored over these things to a ridiculous degree, and we are swimming in so many actual theatrical projection prints that if there were a different version with more standby’s we’d have picked up on that too. There were only ever two standby’s. There are tons of false memory threads here: Luke’s first failed grappling hook throw attempt, Biggs showing up, the scene of Darth straightening out his TIE fighter not appearing the first time, etc. Some things are attributable to outside sources: comics, radio dramas, novelizations, some of it is just mistakes that your memory makes all the time.

Now, Star Wars is a source of more of that than normal, because there were three different soundtracks depending on where and when you saw it (but all of them had two standby’s), there were some very minor print variations (differences in the credits layout, one composite effect for a planet), and the first few minutes were chopped off and replaced by a whole new beginning in 1981 to rename the thing “A New Hope”. So people were always thinking “Heyyy, something’s a little different about this”, which created a lot of validation for the sort of simple errors that you’d normally dismiss, so false memory claims abound.

TL;DR: all of our memories are fallible, this memory you have is wrong but that doesn’t make you a bad person, and Harmy got it right.