Similar thing seems to be going on with torque converters; in shopping for one for a street/strip project, lots of guys are claiming to build them for other guys (some of which are "name brands"), and a couple of places build them by the hundreds or thousands to hear them tell it. Looking on Ebay I see 3 or 4 basic designs marketed under a bunch of apparently-different names.
As far as stuff like alternators, starters, brake calipers and one particular throw-out bearing, I've had better luck with Duralast (AutoZone) than Napa.