Welcome to the boards. Two pups! That's a hand full. Congratulations. I'm sure you're gonna have twice the fun too.
As far as weight goes, boxers vary greatly in their size. But being litter mates, yours will probably be close to the same size unless one was a "runt" and one was much larger than the other pups. You can get a general idea of their adult size by looking at the parents. Otherwise, there's really no way of telling how big they may get until they get a little older.
I have two boxers. Maggie is 10 months old, weighs 55 pounds and is still growing. She's going to be a fairly large girl, I think. Susie is 2 years old and is only 50 pounds and is petite. She probably isn't going to grow much more and is on the small side of the boxer size scale. So, it is hard to tell.
The general "average" for boxers is about 65 - 70 lbs for males and 60 - 65 lbs for females.
Hope this helps. Again, welcome to the Boxerworld forums.