The Amondo Tech batteries are also available "matched" from a production lot run which is a nice little bonus.
Batteries and just about anything that is manufactuered in lots can vary from lot to lot. The possibility exists that bulk batteries from different lots are mixed and you just get a scooped handful tossed into a box you purchase. Therefore, there is a very minimal, but possible chance that when you install 2+ batteries into a device, they might have significant differences in internal resistance that force one battery to excessively draw more current than the other to the point of failure.
I also think its possible places like Surefire or Streamlight just get labels slapped on 123's already being produced by a battery manufacturer. It would seem rather expensive to supplement your company with a battery manufacturing plant and crawl through all the EPA loops when you can just get your label on some high quality product already being manufactured on an OEM level.