Need help from smart people - biamping

Hi, I know some of you are electrical engineers or just knowledgeable - looking for your input. I'm looking at the option of bi-amping my speakers. One amp on the mid-tweet connection and an identical amp on the bass connection. Speakers are B&W N804s. Question is, if you do this do the two amps react to the loads as one amp would, or is it possible that if the two connections (drivers) have different impedences, the bass might be louder relative to the mid-tweet, or quieter? In other words, if the upper end has impedence of 8 Ohms and the amp puts out 100 w/ch at 8 ohms, and the lower end is at 4 ohms, and the amp 200 w/ch at 4 ohms, will this result in a problem in the resulting aural output than would have been experience with a single amp? Thank you.