Unfortunately, at this time, it is an either or scenario. You can sort by Most reviewed or Highest reviewed. With that said, creating a suggestion in our Feature Suggestion forum may be a good idea here to provide some feedback on that.
With that information out of the way, I cannot reproduce on a default test instance the second half of what you're reporting here when you're sorting by "Most reviewed" and getting the weird sorting results (I am assuming "Votes" are reviews 😄 , if they are not may need to check whatever handles that custom operation). May wish to try to disable any third party applications/plugins and switch to an unmodified theme then try again. If you're still having issues then, it may be something more specific we'll have to look at.