Yes, twins are more predominant in certain varieties, but it's not at all uncommon. The plant just branches off when it gets older. I've had some of mine make twins for the first time this winter so I get excited.
I can't quite tell because I don't have those varieties. Did these come from Altman Plants? They supply a lot of big box stores (Home Depot, Lowe's, etc). If these came from Altman, they're likely salicola. Altman usually has aucampiae, lesliei, and salicola. Green one looks like salicola to me, but IDK about the other one.
@sushiwaitress thanks for the info. I don't typically get my plants from garden centre and nurseries. I have had these ones for awhile so not sure where I got them from. I did look on the pot and indeed they have come from Altmans. I will look into further 🙏🙏😊