>> > Maybe I should change the patch to prompt for allowing a dupe install if
>> > that's what someone wants?
>> Not sure it's worth the trouble. It's a sufficiently rare situation.
> I wish that were true.
I think you misunderstood. What I think is rare is the desire/need to
install two different versions at the same time.
Agree. And backing out to an older version is just a reinstall and restart away...assuming the user remembers which version they had before. Perhaps package.el could use an install log users can consult.