Not in one particular instance: if we saw Earth. Current ideas about the shape of the universe don't make this an entirely impossible proposition (just an extremely unlikely one that we'd stumble across our own image from billions of years ago, and I, personally, don't buy it at all).

This idea is covered in an episode of Astronomy Cast. I forget which, but most likely http://www.astronomycast.com/astronomy/ep-78-what-is-the-sha...