One thing I didn't see anybody here mention (unless I skipped something) is that calling srand with the same value to get the same sequence is not portable. Sure, if you run it on the same implementation, you'll get the same sequence, but the algorithm used by rand is completely implementation defined, and switching to a different implementation of the standard library is bound to give you a different sequence.
Calling srand more than once is theoretically fine but you need to be aware of how it works. It's very unlikely you'll have any serious reasons to do it, and if it's to get the same sequence as in the above case, you probably want to use either your own RNG or a RNG library which guarantees the algorithm will stay the same always.
EDIT: just realized a part of the post above says this =/ But yes, that pretty much renders calling srand again mostly useless.