It firstly depends on the hardware as to whether the microphones can both be controlled separately. Secondly, I think that the gnome-media volume control does not yet allow the user to switch between input/output devices to control, whereas pavucontrol does.
So to fix this properly, we would need someone to add a new UI control to the gnome-media volume control applet, based on how pavucontrol does things. Being no UI designer, I don't feel I am in a position to help make this happen.
It firstly depends on the hardware as to whether the microphones can both be controlled separately. Secondly, I think that the gnome-media volume control does not yet allow the user to switch between input/output devices to control, whereas pavucontrol does.
So to fix this properly, we would need someone to add a new UI control to the gnome-media volume control applet, based on how pavucontrol does things. Being no UI designer, I don't feel I am in a position to help make this happen.