If it was truly identical, i.e. same anatomical and biological features, it would be proof that something had transported them there, and would therefore be a branch of life from Earth.
It's like saying a standard opener move in a boardgame is unlikely because there's a lot of other moves available. It's standard move because the game have an optimal set of opener move to achieve victory.
So if another planet with similar environment exist, the range of solutions for self preservation goal might be a tiny subset out of the hundreds of millions of bits of genetic information.