This is more like a remote, uncontacted tribe "discovering" other civilizations via trash that washes up on their shore. Given enough scale, this wouldn't be an unlikely event. Who knows, maybe the universe is littered with bits and pieces of ancient Dyson spheres.
Also, we’ve crashed numerous probes at the end of their lifecycle into many of the objects in our own Solar System. If an interstellar probe from a civilization like our own completed its mission, would it also be programmed to self-destruct itself in a similar manner? I think it’s a highly unlikely series of events, but there is a method to the madness.
