I think this is why those of us interested in this are very much hanging out for results from our explorations of Mars. It's pretty much our only opportunity to see if life emerged twice in the same planetary system under similar conditions.
What are the chances?
On the positive side Mars had pretty much all the ingredients for life (chemically) and had a long enough period for at least something intersting to develop. On the negative side, the environment was still different to ours (gravity, climate, whether, etc).
We still aren't clear on what conditions need to met for like to get going. This is why both positive or negative results on Mars are exciting.
My favourite theory is that life actually takes ages to get started so much so that it started on Mars and finished on Earth (from Mars being impacted and debris making it to Earth). Kind of like a passing of the torch.
Mars: "Crap. I'm dying. Hey Earth, can you take this thing I've been working on?"
Earth: "Yep. No worries. I got this. Will try to send some back in a few billions years. Take care."