Would you like to have a cup of tea?

Sure. Thanks!

Would you like to have a peg?

No, thanks!

When someone offers me a peg, I first deny the proposal and then say thanks. Why? Because he offered me something.

But then, there exists a response...

Thanks, but no thanks!

What's that? Is that second 'thanks' is redundant?

While I understand no thanks (it already includes thanks), I wonder what first 'thanks' is doing there?