Switch between two stream for displaying on one port

My app is capturing two camera, one pipe use nvoverlaysink and second pipe use xvimagesink.
But nvoverlaysink writes video on output buffer and thus I can see this stream.
How can I switch between two stream to display?
Or should I use xvimagesink for both pipes?! How to switch!

I want to see one video sorce, not two video at the same time

Probably nvoverlaysink is not suitable for the usecase. You may try nveglglessink or nv3dsink. Please check gstreamer user guide.