But what u wanna do is not difficult.
You have just to create an additional nn.Module class like:
 model = ur_model #nn.Module
class double_forward(nn.Module):


     init
        self.single=model
     forward(I,T):
        y_1 = M(I)
        y_2 = M(T*I)
       and so on

In the end u can have as many outputs as u want with ur custom loss. You can run the module as many times as u want (but define it only once) paying attention to the order not to create a wrong graph