Some cows will take on another calf easily, others will not no matter what you do...
something I'd be willing to try, is when they have their first calf, take the calf away immediately, and hand milk her a while, then give her two calves once she's used to that and see if that helps..
I had one cow that lost hers (and got to lick it) adopt a calf who's mother had no milk.. She was tame and docile, and milkable, but really didn't want that calf.. After about 10 days she got used to it and let the calf suck, but it was never really *hers*.
The same year I had anothe rcow that had a breech birth, and she went down the chute for me to straighten the legs out and pull the calf, it was dead, and I tossed it under the chute, and let the cow into the corral.. then disposed of the calf. Over the next couple days I brought her into the chute to milk her out and keep her milking. A few days later on the most miserable night, a very stupid cow had twins, so the second twin was rejected, and I was in no mood to mess around, so I brought her into the shop, fed her some colostrum, and put her to bed. In the morning, I put the wet cow in the crowding pen, then brought up the little heifer up the chute. *LOVE* at first sight.. Cow said "Moo" and the calf was hers...