Board Thread:News and Announcements/@comment-3361105-20130322231945/@comment-1511643-20130503013845

.. it does mean they have a completely different personal history and set of characteristics, though. And by the same logic you'd have New Earth and Prime Earth characters together, and like this announcement right here said, we aren't doing that, for precisely this reason.

To quote Hatebunny above, "Yes. Initially, we were going to treat the New 52 versions of characters as the same versions as before. Some of the characters, however, were too different to leave it like that."

An alternate timeline creates an alternate world anyway. We have a Walter West (Dark Flash Saga) page.