Well in the omega verse there are many different possibilities. But I’m pretty sure in order to keep the power in the family a lot of alphas would mate with alphas because they are on top of the social chain. That’s why in many cases of omegaverse the alpha usually comes from a rich and powerful family and the omega is never accepted. I have read some yaoi where they’re both alphas and still have children but every author has a different take on the topic
http://www.mangago.zone/read-manga/okusama_ha_alpha/ This is the one I read

If yall want a kid so bad dojun better sacrifice and be the one who gets pregnant. Alphas can get pregnant right?