Risotto figures out that Doppio must be a Stand user that the boss trusts in deeply because he’s able to hear the noise from a certain Stand. Risotto then uses his Stand Metallic against him. Metallic is able to control magnetic force and attacks Doppio. Doppio uses the part of the boss’s power he received from him. While they’re fighting, Risotto realizes that Doppio’s personality and actions seem to be changing and he realizes exactly who Doppio is.
He just put his hand to his 
throat and defended himself.
لقد وضع يده للتوّ على حنجرته وحمى نفسه
Er nahm seine Hände zur Kehle
und beschützte sich.
Se metió la mano en la garganta
para defenderse.
Se metió la mano en la garganta
para defenderse.
Il a mis la main à son cou
et s’en est défendu.
Ha messo in anticipo
la mano sulla gola per difendersi.
Ele colocou a mão na garganta
para se defender.
и смог достать их из-под кожи.