Following on from this is a lengthy WMG discussing the fates of Classic Sonic, '06 and Sonic Schoolhouse.

If Sonic is interacting with his past self, does this mean that he has two sets of memories of the events? Or that he knows what's about to happen already, because he's already lived through it?.

It made the Crisis City timeline that was cut off by the end of Sonic 06 accessible again, and as a result its version of Blaze and Silver appear as well.

My personal explaination is that it's a result of the Time Eater screwing with time.

It's possible that it's the Silver from Sonic Rivals.

Maybe Silver will always exist, no matter what?.

The same reasoning also applies to Crisis City, which should be Iblis-free.

I think?) then the only future the Time Eater has access too should be lacking Iblis' rampage and Silver as we know him. If the Time Eater ripped out chunks of the current timeline (presumably Blaze, who may or may not be from an alternate dimension, qualifies as being in the current timeline due to hopping in and out it independent of '06 and her home dimension the same can't be said of Silver.

Where exactly did Silver come from? I thought '06 was his main appearance and the one that he's portraying here, but that set of events was wiped from the timeline, making it so that version of Silver never existed.

Sonic generations radical highway