Actually I'm still confused about how Reverse Flash exists. I thought he was erased from existence in the Season 1 Flash finale so that he never existed? Where did this guy come from?
Christopher is probably right, but this could also be Thawne from before he tries to kill Nora.
Everyone who travels through time is a Time remnant.
If you timetravel, you become a second class garbage person, because you can never go home again, travelling into the past annihilates the present in the future, always, every time, it's unavoidable. You will always return to a new/different but similar present, and Barry is too arrogant to accept this, that he is a second class garbage person, because he's always been a little bit of a garbage person.
Even though the time line is constantly changing to reflect all the prodding done by legends and time pirates, Time Remnants keep arriving at the point in time they always did, even if it's not the history they targeted, and the future history they came from is impossible.
Only when confronted with a paradox do they blink out, but they only vanish from time "forward" from the point where they accept their their continued existence is a lie after confronting a paradox... Which might suggest the entire effect if psychological more so than Quantum mechanical.
If this is true, which it probably isn't...
Then there were half a dozen Time remnant Barry's in Flash point, since every Barry that entered the speed force to time travel since the pilot doesn't notice alterations to the shape of the timeline, and reentered the wrong time line thinking that Savage had just blown every one up, or a tidal wave had blow up central city or Barry had gone back to check in on Thawn enhance his speed with tachyons.