Why were twins on everybody loves Raymond replaced after piolet?

Answer 1

Well, the twins weren't replaced, but their names did change.

In the pilot episode, the kids were all named after Ray Romano's real life kids (Ally, Matthew, and Gregory.) However, Romano felt that this was imitating real life a little too much, so the names were changed. Ally's name stayed the same, because she was a more prominent character in the pilot and a change would have been much more noticeable.