Mr. Adventure wrote:
So is the other Walter Walternate?
No. As was driven into the ground this episode, it was the Walter he was and to whom he's slowly becoming once again. Or at least who he's afraid of becoming again anyway.
Which, essentially, is
Walternate in theory. But never having had his brain tinkered with is only one aspect of Walternate. It was his obsession with recovering Peter from Walter's universe that really drove the two down separate paths.