My wood front door has polished brass handleset hardware which uses
the same key as the back door which has an entry knob & single
cylinder deadbolt combo. Since the polished brass is peeled due to
weathering (mostly hot sun), I'm thinking of replacing it with the
same (if possible) but if I replace both front and back door hardware
simultaneously, can I get one key for all (like the old ones are) or
do I need to get a locksmith to rekey both doors to use one key? I
don't know if I can buy a complete front/back door hardware set
similar to the existing in one package so that they share a key?

If I need a locksmith, any idea what this costs? Maybe not worth the
cost for the convenience of one key?