I don't have a yorkie who was a twin. Although Maddie and her sister still look and weigh the exact same. They were very very close when I took her home. She and I bonded instantly, and I don't see why your puppy would have any trouble at all.
Infact I know twin girls (people) who were adopted to seperate homes at about 4 months of age, and they had no problem in their new families, when they met as adults, they really didn't care for eachother all to much
