Text (SA): Until end of turn, creatures you control get +5/+5 and gain first strike, lifelink, and trample.
The set of creatures affected is determined when this resolves. [Shards of Alara FAQ 2008/09/23]
Multiple instances of First Strike and Trample are redundant, but if a creature ends up with two copies of Lifelink, each of them will trigger separately when it deals damage. [Shards of Alara FAQ 2008/09/23]