Unfortunately this is because of marketing stunts that these companies do. The UBPN production was stopped before these BP chips were properly introduced in the market so I am compelled to dance to their tune. Atmel in India has done something even funnier, most of the chips are from the China plant and they are buggy. But what is worse the datasheet of all three chips shows specs of I/O matching. So it looks like some spec not mentioned in the datasheet has been modified.