which channels ?
some say the front 3 channels should be identical or at least the tweeter and mids should all be identical across the front sound stage
some say it should be that way for every channel and some say the rears are not that important
if you're looking for the most seamless coherent panning of sound from channel to channel, especially for multi-channel music, try to stay identical or as close to identical as possible
but this will all come down to personal taste. there are lots of people who are perfectly happy with mixing different types of speakers front and back or center/mains etc.
it all comes down to personal taste