Hello,
As a user, this is the response I received from BM support on the same problem:
From Tech Support:
"I apologize for any confusion or miscommunication. The UltraScope is not designed to work in the same system as a DeckLink capture card, as noted in the Minimum System Requirements on our Support site here: blackmagicdesign.com/support/detail/supportnotes/supportnote?sid=3956&pid=4022&snid=6333&isSDK=false&os=win
What you could theoretically do rather than uninstalling/installing the cards, if you simply uninstall/reinstall the drivers this could be be an easier solution than physically swapping cards, though I do understand this isn't the cleanest solution either. The UltraScope is designed more as a solution for standalone systems. Again, I do apologize for any miscommunication regarding this set up."
I hope this helps.