I don't know what it's like in other countries, but in Sweden there's a law that states every companion bird must be kept in the company of another bird. This other bird has to be of the same genus. Another sub-species is alright, you can for example keep a Senegal (poicephalus senegalus) with a Meyers (poicephalus meyeri), or a Blue-headed pionus (pionus menstruus) with a White-capped pionus (pionus senilis). I think this is a good law as it makes sense for a lot of reasons. They have very similar nutrition needs, their temperaments might be more similar, their aggression level as well, beak size... I suppose it's more likely they become friends if they're of the same genus, as they probably speak a similar "language" and have similar needs. And if they wouldn't become friends and would end up fighting, similar beak sizes is a good thing.
Although, having parrots of the same genus is no guarantee that they will become friends, some parrots don't get along with other birds at all, no matter what species/genus they are. So if you plan on getting another parrot, make sure you have the space and time needed for two. Two cages, enough time to have them both out of their cages, but separate from each other, and so forth.
With all this said, I wish you the best of luck and hope you find what you're looking for! It might take time, but if you get a second parrot and your two birds become friends, I promise you that you're going to have a great time. There's no thing like seeing your bird playing, cuddling and having a good time with a feathered friend
Best regards,
Sara, Penny & Joy