They won't send you a pair, unless they have ones that are already bonded, which they will sell at a higher price and call "a pair". The clownfish will sex-change, so you'll very likely end up with a pair as they mature.
All I saw on your other thread for "pairs" were the clowns and the Royal Dottys...the Dottys you'll want just a single one. Unless they are a mated pair they will fight.