Blackmagic Decklink Duo2 Audio Capture Problem

Hello!
I try to connect two video signals(with audio) to the Decklink and select one video on UE4 by using UMG.
I simply two Media Bundles put on the level view port. The video signal is no problem.
However the Audio signal is so noisy. (I guess two audios are mixed.)
I try to set one Capture Audio Flag is False by the Media Bundle GUI, but it could not be improved.
So, I try to delete one Media Bundle, then that is improved.
Is it impossible multiple video signal(with audio) put on the level view port with a clear sound?

Thanks!