Like it's been said before, both of them are parallel existances.
Raven is the result of something Axl does. That something apparently results in
a horn through the head...
Axl is the past, Raven is the future, albeit one from an entirely different timeline/reality.
You originally had GG1, then the timeline introduced in the one Drama CD where Dizzy
went evil and was leading the Gears parallel to Sol leading the resistance. That was
the "correct" timeline.
Once I-no showed up and saved Ky, time/reality was shifted. So the Raven in that
world, aka Axl Low, was brought into the *new* timeline, the one with our normal
looking Axl.
And well, since you can't have two of the same person in the same realm of existence,
*insert chaos theory here*, one off-sets the other, a.k.a. Axl being forced to time slip.
I would assume that if something were to ever happen to Raven, Axl wouldn't be caught
in a time loop. But then again, time travel, shoot, any science-fiction involving time
is just...hell I'll let the emoticon speak for itself. --->