They’re not twins

[Ky hills]

This cow and the other calf's mother calved within a few days of each other. Have seen this calf nursing her several times, but never the the other calf nursing the other cow.
When she stopped nursing the black cow she went to her real mother and nursed her. I think she's just figured out that she can sneak extra milk from this SimAngus cow.
I once had a registered Charolais cow that you could often find four calves nursing her at once.

 

[TCRanch]

I have a few cows that won't allow other calves to rob until their calf is a few months old, but after that, it's a buffet.

 

[Farm Family]

One of our top end milk producers with an udder the calves drool over has learned to back herself into a corner to guard her wares. She has a dairy udder. Gosh I wish she'd adopt one or two but there is not a chance. Her calf and her calf only! She is seven this year and will not be stolen from. It is funny. I really should grab a pic cause how she figured that out I will never know!

 

[50/50Farms]

If one's got it to give then it ain't so bad.