Oh dear, I've accidentally twin mum shamed as a twin mum! Sorry!
If they've never complained, you're fine! I have a family member who's a twin, and he guilted me into making sure I made two cakes for my twins' first birthday onwards because his mum had always actually refused to make one each for him and his brother. Despite both he and his brother liking and disliking different flavours. That made me so sad I made two. But there was FAR too much cake, because to my mind I couldn't make them smaller, because that was just as bad!
The grandparents in this story had INSISTED on bringing the cakes. Then done the maths and decided two was silly. My friends strongly felt two cakes were important and were really upset. That was their hill to die on, and it had been ignored.
I happily call my twins "the twins" in the same way other people insist on calling them "the kids", or using names every time to avoid "the twins". I don't have an issue with it, some twin parents have that as their hill to die on. I don't like "the kids"; it jars for me. Mine are B/G twins, so I can't call them "the boys" or "the girls".
I always do one present from the pair of them for a party, though I'll pay more than for a single present. (Sometimes double the budget I'd have done for one, but depends on how lucky I've been with the purchase price. Same as a singleton might get a cheap present due to budget constraints or purchasing luck.) My reasoning for one present will always be because one gift will always be liked more by the recipient as well as by my twins. I'd like them both to have given equally. I'd wrap more than one item in one parcel.
As you can see, as twin parents, we're all fucking nuts. All trying to live our lives. All paranoid about being judged for being "too" something, or "not enough something" by singleton parents, or by those who produced their children in single doses. Or I'm speaking out of turn to speak on behalf of however many twin families there are in existence, and being as bad as those I'm saying can be critical. I had a few "fuck those people" moments over the last few years when people couldn't understand why I was perceived to have "special treatment".
In short, that's why this is so long. Because I'm now worried I offended another twin mum. (Just kidding, I know I just need to send you comradely twin mum vibe nods, and we'll both move on to the next thing! No time!)😘😂