Do you have to have the same game to play multiplayer on the ps3?
Yes you do, but many times the same game might have different
titles like game of the year edition or Greatest Hits edition. They
are the same game. Editions are not different games and can play
similar maps together. The old Hardened Edition of Black Ops could
play the World at War Maps in Multiplayer with only other people
who had the maps, but the could play other maps with the people who
had the standard edition.
If someone has a DLC that includes maps that you do not have you
can not play any of those maps with them, but they can play
multiplayer with you on any map or level that you both have