There's something about my original NES, that I've owned since childhood, that makes the wall in stage 4 of Double Dragon almost impassible. I thought for years that the game was designed this way until I heard of other people getting past it like it was no problem. Playing it on my toploader and modded toaster it's a breeze, but if I plug that same cart into my original Nintendo, that wall turns into Chuck Norris. I've literally gotten there with full health and all my lives and been completely obliterated.
As strange as it sounds, after all these years, I wouldn't want it any other way. If my original NES let me through that wall area easy, I would honestly be disappointed. As for a real reason for this, I can only assume it has something to do with the ram chips and their initial state at startup.