So!! I tried to alter the code you provided to make a v simple pairing generator (for a particular fandom of mine, Ensemble Stars, with a biiig ensemble cast perfect for something like this) BUT it does have a clear flaw when used for that purpose: the code allows for the same name to be picked twice, generating selfcest pairings! For another more sci fi oriented canon that might actually be vaguely plausible, but not so in this one.

So: is there any way to make sure the second (or third) name picked is different from the first?