like i said, both of my children doubled by 3 months, they were both close to 7 lb when they were born, and were 14 and 15 lb. at 3 months.
i think it has alot to do with their weight at birth. it seems if they are smaller (like mine at 7) then they double early, but i haven't really heard of many 10 lb babies that have doubled that soon.
just because the double early or are huge when they are little doesn't mean they will continue to be. my first son weighed 6 lb 13 oz when he was born, then 14 at 3 months, 18 at 12 months and has stayed at 32 for his third and fourth birthday. he grew fast at first and then slowed down.
baby, i can't believe your baby is that big. He must be a great eater.
mine is 13 months and 23 lb., he is a little chunk. he is wearing some 2T which my 4 year old was just wearing last year.
good luck with you babies and just remember every baby is different and that it is still normal.
have a great day.