Well done for cataloguing the differences. That makes everything much clearer.
My thinking about the Sunday Al-teen 45 is that label owner, Bill Meeks, only pressed up a small number at a time, maybe to reduce outlay and possible wastage (in costs) of any 45s that didn't sell.
First run sells well, so he gets more pressed. That also sells out, so he does the same again. Interest grows, probably because of radio plays. Meeks seeks out a better deal for the pressing of more copies.
If he only had a small number pressed each time, it's likely he would have had roughly an equal amount of labels printed. Each time a new batch of 45s is pressed, a new set of labels is also required.
The first two presses show that Meeks was distributing them himself. Other presses do not indicate this. Perhaps he did a tie-in where the 45s were pressed and distributed in a single deal via a distributor. No idea if this was something that happened back then, but it would seem logical to have places that provided a one-stop-shop kind of service.
Also, the first two presses credit only one person as arranger - M. Thompson (with 'M. Thomas" simply being an error). Perhaps as record sales grew, and making a presumption that anyone involved in arranging to tunes was getting a cut of profits, J. Powell was added with the intent of making money for someone involved in the management of the label, but not necessarily actually involved in the arranging.
While the Al-teen 45 is pretty common, there are also plenty of the Chess presses out there. The site ValueYourMusic.com - a Popsike copyist (I can't get into Popsike at the moment as I've used it too much today!) - lists 44 of them going back only as far as September 2015.
That also makes it pretty common.
Link here:
https://www.valueyourmusic.com/vinyl?q=sunday+chess&sort=date_end_asc&utf8=✓