Hazy said:
Something tells me that humanity will still screw it up and end up waging war.
Personally? That would make relating to them even easier.
Are you kidding? We'd encounter a species like us, but from a different place. Historically speaking, the thing humanity does when confronted with something strange is?
Nevermind the fact that they are supposed to be exactly like us, and only one side needs to declare a war to get the ball rolling. Basically, the odds of a war are pretty big, really.
Though, to be exactly like our world, they'd need to have had the same leaders(if equal countries), same religious figures, hell, same planetary, nay, solar setup.
I mean, what if they're from a system with 5 planets? That's the Greek and Roman religious pantheons
fucked right there. When those are messed up, it's already pretty impossible for them to advance just like us. Constellations also played a big part in early religions.
The only way I could see this happen is alternate dimensions, but then they're not really aliens.
tl;dr: Small chances are small. War is pretty damn likely.