At the very least MC-alt had the guts to ask Sui-alt out while MC-prime didn't until jarred by this incident. We don't know how much Sui-alt differed from Sui-prime before the two alts started dating. Diet, activity, and "activity" changes could all be part of the reason both the personalities and bodies differ.
Nobody's talking about it but shouldn't they have the same mum? Other Sui hasnt seen her own mum in at least a month?? You'd think she'd have some kind of reaction to that