You're not reading the calendar right. Those are listings for specific parties that take place at Privelege and Space.
I think the one at Space is a mistake, actually, as La Comunidad (Space on Fridays) actually opens in June. At Privelege, it is the Ibiza Rocks party that opens on July 22.
As for doing more than one party in one night, of course you can if you don't mind shelling out money for 2 tickets per person (and the extra taxi ride). Since tix aren't cheap, I don't know many people who do that...