No, I didn’t try them both at the same time. 
Back in February, I installed KVM under OpenSuse 15.6, on a Dell 7010 with an I5 and 32Gig of RAM. I had to post here for a bit of help, but got it working; then I discovered that KVM insists on using (I think it was) TigerVNC, which is incompatible with RealVNC, which I MUST use for my employer. So … after all that work to install it, I had to uninstall.
A few days ago, I wanted to grab some screenshots of an install for a good friend and coworker in Denver, CO. I remembered that KVM had been vaporized, so I said, “Ah! VirtualBox.” I installed it with Yast, made myself a member of the VBoxUsers group, and rebooted just to be safe. Sure enough, it seemed to work.
After grabbing my screenshots, I removed VirtualBox with Yast, and that’s when things went to crap. My network died, so no Internet. (For the record, I use Wicked, not Network Manager.) Entire files were missing from some directories. Needless to say, it was kind of difficult to reinstall missing apps and troubleshoot with no Internet, so I just reinstalled OpenSuse 15.6. Thank the Lord, that worked. I kept my /home directories and everything fell back into place.
I wish I had more information, I might file some bug reports. I was under pressure to get a job done before Christmas, so I really had no choice but to take the quick route and reinstall OpenSuse.
Give me a few days to catch my breath and I’ll see about upgrading to 16.0. 
But this is a heads up for anyone else who runs across this. I can’t see any reason why uninstalling VirtualBox should tamper with so many files, but there you go.
