State tax filing

I was checking whether it is better to file federal as married joint or separate, and the MA state as married joint or separate. I noticed the following when I checked the different combinations:

Total income: federal joint > federal separate for me + federal separate for my wife

Total AGI: federal joint > federal separate for me + federal separate for my wife

 

How come the separate federal incomes and AGIs do not add up to be the same as the joint amounts? Or am I missing something?

 

Thanks!