Yes it's him. He broke the time barrier and jumped back to past. From IMDb
Mark creates a Tsunami that could destroy the city and Barry shows
Iris his powers. Barry tries to go as fast he could to create a wall
of wind and accidentally time travels back in time to where he was
trying to get to the morgue.
And from the conversation it's clear it's him
Dr. Harrison Wells: You ruptured the time continuum, didn't you?
You're experiencing temporal reversion. Barry Allen: Yeah! Dr.
Harrison Wells: How long?
Barry Allen: Uh, a day and some change. It's
like I'm living it all over again.
Dr. Harrison Wells: Yeah, well,
that's good. That means there's not too much you could've messed up
yet. How did this happen?
Barry Allen: I-I don't know. I mean, I was
running faster than I've ever ran, and the first time that I lived
this day some really horrible things happened. There was a tidal wave