Well, you can do that if you can code it.
For example, gradient clipping is nothing but a normalization on the gradients. You can pick gradients after calling backward()
If you are capable to find a good metric to compare them you can propagate only gradients for one of the signals.
However, I don’t believe gradients are gonna be the same in most of cases. Maybe it’s easier for you just to detach the backprop from the second network such that only signal 1 flows.