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.
I learned from my mistake of 
letting you chop off my right foot.
تعلّمتُ من الخطأ الذي نجم عنه
قطعِك لقدمي اليُمنى
Ich habe durchaus daraus gelernt,
einen Fuß verloren zu haben.
Cuando me cortaste ese pie,
aprendí de mi error.
Cuando me cortaste ese pie,
aprendí de mi error.
J’ai commis une erreur
qui appelait une correction.
Ho imparato dall'errore
che ti ha permesso di tagliarmelo via.
Eu aprendi uma lição quando
você arrancou fora meu pé,
Проанализировав ошибку, 
стоившую мне ноги, я придумал,