> RPX400 and Kentmere 400 are different
Yes they are. RPX 400 is a batch of film, which someone ordered form Harmann. It is based on Kentmere 400, but the recipe was modified. The contract failed and the film left over.
The bad side: It exists only this single batcht. If it is sold out, we never get it again.
I suppose that explains the different emulsion numbers on different batches of RPX 400 over time.