If a permanent has multiple instances of graft, each one works separately.
July 13, 2013 · Magic 2014
rule 702.58b not present in this release
June 17, 2011 · Commander 2011
If a spell has multiple instances of ripple, each triggers separately.
February 4, 2011 · Mirrodin Besieged
Players may activate mana abilities and take special actions while a spell with split second is on the stack. Triggered abilities trigger and are put on the stack as normal while a spell with split second is on the stack.
October 1, 2010 · Scars of Mirrodin
Players may activate mana abilities and take special actions while a spell with split second
February 1, 2010 · Worldwake
Players may activate mana abilities and take special actions while a spell with split second is on the stack. Triggered abilities trigger and are put on the stack as normal while a spell with split second is on the stack.