My mates and I got into a very heated debate over this yesterday. How many variations of the same Planeswalker can you have in an EDH deck?
1 copy of each card. So for example, if your deck is blue, you may have
1 {Jace Beleran},
1 {Jace, The Mind Sculptor},
1 {Jace, Memory Adept}, and
1 {Jace, Arcitect of Thought}
All in the same deck. Keep in mind you can still only have 1 on the battlefield at the same time, because of the planeswalker subtype name rule.
RESOLVED
Yeah, of course. My friends were all telling me that you could only have one of each subtype in the deck. I was like "NOOOOOooooo....you're wrong!"
EDH rules are one of each actual card, subtype is irrelevant.