I understand the premise is that their tech is the same as our tech. Since we discovered each other nearly a century ago, the tech that we would have now would be considerably more advanced than what we actually have now if resources had been spent differently.
The issue is trust. Can we trust them and how do we know for certain that we can trust them? This is difficult enough with other humans let alone a completely different species. We have no choice but to approach this situation from an anthropological viewpoint because that's what we are. We fear them because we know what we're capable of.
Let's say we want to send a probe of peace that has information about our history as a species and life on Earth much like Voyager's Golden Record. Because we have no way of knowing, as of yet, how they evolved and how they look at the things you have to understand the consequences of such a seemingly peaceful gesture. Anything from their point of view could be seen as hostile. The high speed approach of a projectile could be seen as an attack. The scorching of their sacred desert burial grounds can fill them with hate. Leonardo's Vitruvian Man could be seen as a Martian "come at me, bro".
I'm not saying a peaceful outcome is not possible. I am saying, given our history with members of our own species, that to be confronted with an alien race who has the same potential destructive capability as us but with whom we cannot communicate properly, destruction of one species is seemingly inevitable.
