4 year old imitating 2 year old brother

Dear Naomi, I have read your book, and spoken with you once over the phone. I gained so much from both experiences, and hope to be able to speak with you again. Until then, I hope you might shed some light on our situation. We have 2 boys, 2 years and 2 weeks apart. The younger one is learning multiple words, daily. We are excited to be able to understand him better. The 4 year old is very talkative, and so interesting to talk to! For the past 6 months, he has been imiating his brother's baby talk. It is very frustrating. I fear he will "forget" how to talk like himself, I worry he is doing the imitating becuase he doesn't feel special enough as he is, and I worry he is "mising out" by being home with us and not around older kids. When I read this, I realize how it sounds. I need him to know he is special and doesn't need to imitate his brother to get our attention or love. I have told him this. If I just react the same way to him that I do to his younger brother instead of asking him to ask me "in his words" will this help him to move past this phase?Did he not get the chance to do "baby talk" because he learned to string his words together into sentences very early? We are at the end of our rope. I find myself saying multiple times a day "God didn't give me twins." We need help!