virtualbox[.]org/wiki/Testbuilds
Found this while working with VirtualBox, investigating its security. The current version Guest Additions cannot be uninstalled -- it's a bug. And an earlier version of the Guest Additions is also listed in Settings -> Apps -- also a bug. You can download a newer ISO of the Guest Additions from the page linked above [along with VirtualBox is you wanted]. I copied the new ISO to the Program Files\Oracle\VirtualBox\ folder, set that ISO in the virtual optical drive, and installed those new additions, which will uninstall. It likely has other benefits, but I haven't checked it out too much yet. As far as the old entry showing up in Apps, look for this key using Regedit, making sure the value for the version number is 7.0.20, and delete the key.
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Oracle VM VirtualBox Guest Additions]