unless not

Could you tell me if these sentences below have the same meaning??
I'm not sure the usage of "unless not"...

1)I'll be surprised if Ken doesn't have an accident. He drives too fast.

2)I'll be surprised unless Ken doesn't have an accident. He drives too fast.

I'm confused...

But as far as my understanding,

2) can be said like:

3)I'll be surprised if not Ken doesn't have an accident. He drives too fast.

So, 1) is not the same with 3)...

3) means "I'll be surprised if Ken has an accident. He drives too fast."

??

Thank youi!