Do cows gave birth to two calves?

They can, but they won't conceive a calf. It's just like with two women having sex: they can arouse each other to orgasm, but that won't mean that they will conceive a child between them. In the case of the bovine world, if a cow is in heat, she can (and will) ride other cows or heifers and other cows and heifers will ride her, but because they don't have the "tools" necessary to get her bred, she cannot conceive a calf. That's where the bull comes in, or the AI technician.