Only One Tuner of my Hauppauge WinTV-dualHD works under 8.95.2

Hi, thanks for clarifying.
I’d rule out the Stick itself: Using Windows, I can flawlessly watch two channels at the same time. No glitches whatsoever.
I’d suspect the driver.
As soon as Kernel 4.18 is available with some Kodi distro, I’ll see: Since 4.18 (or even 4.17) the stick is natively supported.
Cheers
Hauke