[Ubuntu Unity 16.04.5 / Cairo Dock] e.g. two clickable and runnable Opera buttons side-by-side in my Start Menu? I tried uninstalling the Opera version I don't use (Opera v12), the terminal says I have two versions of Opera installed (but says "cannot find" when I try to uninstall the old Opera), and the software center says I only have one version installed (Opera-Stable v55) despite two Operas (12 and 55) being on my Start menu and both being fully operational.
I once ended up with 2 minecraft launchers with the same problem of software saying I had only one, but both worked, and I had no problems and my computer ran like that for a few months until windows 10 wiped my drive on accident. You should not have any stability or security issues if there are two of the same program different versions