Con- they share illness repeatedly, they egg each other on, one has a bad night usually means they both do, no sleep for a longer period of time, jealousy, even more hyper vigilant, going out alone is incredibly hard with two babies, no alone time, someone is always touching you, sexy time has to be scheduled, getting kids on same schedule is hard to keep up.
Most cons happen early but end when the kids become more self reliant.
Pros- they love each other from a very early age, they can be each other's best friends, hand me downs, you know what to expect, already have most equipment
Most of the pros from having multiple children don't come until the children are older and a little more self sufficient. We always had each other's backs, we always had a play mate, if we got scared in the middle of the night we went to a sibling instead of mom or dad, they help each other with little tasks (water, cleaning up, bed time). Always have someone to walk to school with and walk home with. Always have someone to get in trouble with.
I wouldn't trade it for the world.
Angela