First question do all the lambs have the same flock number ? a dealer may have made up a group from various farms . You have 2 choices the easiest , fatten them and resell in the spring , you can leave the tags as they are and maybe at the end make a small profit , provided you didn't pay a lot for them . Yes you can upgrade to double red eid tags ,so long as you can trace them back to holding of birth . The license you have should have the sellers holding number so that's a start , then hopefully they were sold at auction by the breeder , the auction mart should be able to help you get this information .