Actually they will reproduce. They will also carry a gene for multiple births. A sheep that gives birth to twins will pass that gene to its lambs. The ram lamb will then pass that gene to his daughters. I know of many that do have twins in sheep. A friend that bought my flock in 2006 had a set of triplets this spring. Not real rare in sheep. Cattle only have triplets 1 in 150,000. Growing up we had Angus cattle. Several had twins. We kept the calves, one a bull. Cows taht have twins usually also produce more milk. Thus even if their calves have singles, they gene for more milk production is there.THEY CLAIM THAT TWIN AND TRIPLE BIRTHS WILL NO REPRODUCE, I DON'T KNOW
If I were him, I would definetly keep the heiffer calf and advertise the two bull calves as herd sires. That gene for multiple births is rare and valuable.