Recently I ordered many 28BYJ-48 small stepper motors.
I have since found out that not all of them spin the same direction when driven by the same pulse sequence -
91 of mine turned clockwise, and 5 turned counterwise!
The markings on the majority were the same - 15031801 on the label.
The other 5 had a different number, something that looked like an 8 digit serial number. Mine all happened to be 91416xxx, with 5 different numbers for xxx.
So if you're ordering multiples of these, check the pictures - don't mix 15031801s from one source and unique numbers from another source.
It's certainly handleable in software, but I have enough going on that I didn't want to deal with having to treat 5 motors differently than the rest. The 5 are being returned and replacements have been ordered.
I suppose I could have also depinned the connecters and rearranged them, but as I noted, I am busy enough already.