Having multiple space ports doesn't give you any advantage I don't think, as their sole purpose is to ferry resources to your stockpiles.
I haven't tried it on the same planet, but multiple ressuply depots in the same system will have their effects stack (ie rate of resupplying ships in the system will increase) I guess having more than one on a planet will boost your supply reserves and the rate supply is generated on that planet as well
Not sure about Med bays though haven't tried yet.
EDIT: Manual says that only 1 med facility per system is effective.
Having multiple space ports
Having multiple space ports doesn't give you any advantage I don't think, as their sole purpose is to ferry resources to your stockpiles.
I haven't tried it on the same planet, but multiple ressuply depots in the same system will have their effects stack (ie rate of resupplying ships in the system will increase) I guess having more than one on a planet will boost your supply reserves and the rate supply is generated on that planet as well
Not sure about Med bays though haven't tried yet.
EDIT: Manual says that only 1 med facility per system is effective.