So you want to make sure Mackie HUI pings are only routed to your HUI device and that they are not routed to your other generic device.
As an example, set up your HUI device in Cubase to go to and from BMT 1 and have your generic device setup to go to and from BMT 2. Then the 2 devices will not interfere with each other. In MT Pro you can set up routing of these two virtual ports to go to different attached devices.
For more information about device selection, see this tutorial.
I just recently posted a project on a similar question where the user wants to use transport messages with Reaper and other messages with Mixing station. The concept is similar when it comes to MIDI routing. You can review this post.
Steve Caldwell
Bome Customer Care
Also available for paid consulting services: bome@sniz.biz