Please spoil DC JLA v3 #51 to me (unboxed spoilers)

I happened across v3 #50, which had a bit of a cliffhanger ending. The JLA revealed their secret identities (those who had them) to each other in the batcave, Batman/Bruce Wayne among them.

Then, the batmobile drives up, and someone who appears to be Batman comes out.

Who was that?

Short version–some aliens have a sort of mobile wish machine that’s running around. In the previous story arc, someone said something about how tough it is to keep a secret identity and the thingie split the JLAers with Secret IDs into two people. They learn that they need both sides of themselves working together to survive (duh) and eventually rejoin, beating the aliens and the wish-machine.