mixer with not-real-differential rf signal in?

if the input rf signals of receiver mixer are not differential, say there is phase error about 20deg(e.g. 0deg and 160 deg respectively), what will happen to mixer performance?
due to the function of mixer , the output IF signal will be accurately differential.
I am afraid the linearity will be deteriorated.

slightly poorer conversion gain. Obviously, if the signals were 180 degrees out of phase, the differential input would completely cancel them.