birds of a feather; villains of the same stripe
Idiomatic expression meaning people who are alike, especially in a negative or suspicious way. Often used to imply that bad people share similar traits or are in cahoots. The literal meaning is 'foxes of the same hole'.
See also: 同じ穴のムジナ
Those two are birds of a feather.
You could say swindlers and thieves are villains of the same stripe.
The expression likely originates from the idea that foxes (or badgers) sharing the same den are similar in nature, extended metaphorically to people of the same (usually unsavory) character.