clamav uid and gid

I am just working through the howto for installing spamassassin and clamav on Panther server. Is there any particular reason that clamav is given uid 26 and gid 26? these ids are already assigned on my machine: uid 26 = Printing Services, gid 26 = lp Do the uid and gid absolutely have to be the same? Should I not be using ids greater than 500? Thanks, Miles