Previously, planeswalkers were subject to a “planeswalker uniqueness rule” that stopped a player from controlling two planeswalkers of the same planeswalker type. This rule has been removed and planeswalker cards printed before this change have received errata in the Oracle card reference to have the legendary supertype. Like other legendary permanents, they are subject to the “legend rule” (see rule 704.5j).
January 25, 2019 · Ravnica Allegiance
Previously, planeswalkers were subject to a "planeswalker uniqueness rule" that stopped a player from controlling two planeswalkers of the same planeswalker type. This rule has been removed and planeswalker cards printed before this change have received errata in the Oracle card reference to have the legendary supertype. Like other legendary permanents, they are subject to the "legend rule" (see rule 704.5j).
September 29, 2017 · Ixalan
Previously, planeswalkers were subject to a “planeswalker uniqueness rule” that stopped a player from controlling two planeswalkers of the same planeswalker type. This rule has been removed and planeswalker cards printed before this change have received errata in the Oracle card reference to have the legendary supertype. Like other legendary permanents, they are subject to the “legend rule” (see rule 704.5j).
May 1, 2014 · Journey into Nyx
If a player controls two or more planeswalkers that share a planeswalker type, that player chooses one of them, and the rest are put into their owners’ graveyards. This is called the “planeswalker uniqueness rule.” See rule 704.
February 1, 2014 · Born of the Gods
If a player controls two or more planeswalkers that share a planeswalker type, that player chooses one of them, and the rest are put into their owners’ graveyards. This is called the "planeswalker uniqueness rule." See rule 704.
July 13, 2013 · Magic 2014
If a player controls two or more planeswalkers that share a planeswalker type, that player chooses one of them, and the rest are put into their owners' graveyards. This is called the "planeswalker uniqueness rule." See rule 704.
September 30, 2011 · Innistrad
If two or more planeswalkers that share a planeswalker type are on the battlefield, all are put into their owners' graveyards as a state-based action. This is called the "planeswalker uniqueness rule." See rule 704.
June 17, 2011 · Commander 2011
If two or more planeswalkers that share a planeswalker type are on the battlefield, all are put into
April 1, 2011 · Duel Decks: Knights vs. Dragons
If two or more planeswalkers that share a planeswalker type are on the battlefield, all are put into their owners' graveyards as a state-based action. This is called the "planeswalker uniqueness rule." See rule 704.
February 4, 2011 · Mirrodin Besieged
If two or more planeswalkers that share a planeswalker type are on the battlefield, all are put into their owners’ graveyards as a state-based action. This is called the “planeswalker uniqueness rule.” See rule 704.
October 1, 2010 · Scars of Mirrodin
If two or more planeswalkers that share a planeswalker type are on the battlefield, all are put into
February 1, 2010 · Worldwake
If two or more planeswalkers that share a planeswalker type are on the battlefield, all are put into their owners' graveyards as a state-based action. This is called the "planeswalker uniqueness rule." See rule 704.