Dick Turpin, Two of a kind, you scratch my back, I'll scratch yours

Dick Turpin, Series 02, Episode 03. The Blood Money

Dick Turpin: Look at them. Two of a kind.
Swiftnick: What do you mean?
Dick Turpin: Well, you scratch my back, Colonel de Coursey and I'll scratch yours.

(Two/three, etc of a kind = two/three, etc people or things that are very similar)
(You scratch my back, I'll scratch yours = used to say that you'll help someone if they agree to help you)