I install RollBack Rx on VMWare Workstation quite often, I've never had an issue.
installing Reboot Restore when I already have Rollback RX Home told a prompt to uninstall Rollback
RollBack associates with your MBR, since you only have one MBR, you can only have one program associated with it. That's why you were prompted to uninstall.
I don't think it's that Rollback is incompatible with virtualization software, you're doubling down on similar software. Toolwiz Time Freeze while it touts itself as 'virtualization' is more like Deep Freeze or Reboot Restore Rx imo. Especially if programs like Toolwiz Time Freeze associate with your MBR. Aside from the technical aspects, why would you run RollBack and Time Freeze when they are somewhat similar.
It's a real simple fix for this, if you want to run RollBack in a virtual environment, I'd recommend you find a dedicated VM service. There's free VM services out there like VMWare Workstation, but I wouldn't classify Time Freeze as one, and I suspect RollBack isn't as well.