How is it that Rebecca was able to keep Tommy 2 from finding out that he is a clone? There was this girl who was known to be a clone and therefore got avoided by Tommy 2 and his former friends. Then those two notorious mothers talked with that girl who works at the hospital which is when they find out that Rebecca's son is a clone as well, so in the end no one shows up at his birthday party. ...And he just never went to school again after that? Or outside without his mom? So he must have been home schooled then, but there got to be at least one moment where he was outside alone and asked the others why they didn't want to be friends with him any longer.
I have two explanations for this (though I admit it's a good question!)
1. Even though mothers knew, I don't think anybody wanted to be the person who revealed the secret to Tommy 2. At the meeting about the cloned girl, the other moms tell Rebecca that human replication is "too complicated" for their children and they didn't want the kids dealing with it first hand. Although their kids were obviously aware of cloning, I think the mothers preferred to ignore the subject altogether and probably wouldn't want to explain Tommy 2's situation to them. The moms most likely lied to their children in order to shelter them.
2. Almost immediately after the other mothers find out, Rebecca moves Tommy 2 away from where they were living. I'm not sure how far away they moved, but it was definitely far enough away to where he wouldn't be in the same school district or faced with the people who knew he was cloned.
Although I'm adopted, my three cousins never knew they were adopted. *I* knew that they were adopted from a young age, infants and toddlers. I was tasked never to tell them and I never did so. I figured they'd learn about it one day and they did. Unfortunately, they learned the secret at the worst of times. They were very angry that they hadn't been told the truth by their parents. It's not as though they would have been surprised; their folks were foster parents for many other children.
The oldest daughter had a car accident in which one of her own children was tragically killed. She went looking for her own birth certificate for some reason and when she found it, the information was there for her to see that she was adopted. It was as easy as that for her to uncover the family secret. She was beyond betrayed in her feelings.
It took several years for her to calm down enough to speak to her mother again. Don't keep family secrets. It's not worth it. Tell your children they're adopted; they'll find out eventually. I always knew. It's for the best.
My point is, how would he have known he was a clone? No one knows when they are adopted. There's no X marking the spot or an automatic birthmark or trademark telling you that you don't belong. Well, there was with me. I was the sole redhead in a group of people who were either blond with blue eyes or had dark hair. I was definitely a sport.
The film deliberately put an X to mark the spot. Remember Tommy's remark that 'copies' had a funny smell? Wouldn't his playmates have noticed -- and told him -- that he did too?