I usually name triplets/twins same as my other sims, which is, I try and name every generation after the next letter of the alphabet, and make their first vowel of the name go alphabetically too. Like for example (not names I normaly use though) Aaron, Aeris, Aine, or Bailey, Bella, Bianca, and so on.
So considering my short attention span, I would never end up with a name like Hyperion, because that would indicate like, 8th generation, 6th born.
On a side note, my friend is wearing a "Thing 2" shirt today. I of course asked why his girlfriend was not wearing "Thing 1" shirt. :D