As part of messing up packaging Ruby on Rails, I ended up duplicating
some packages, and this prompted me to look if any duplicates made it in
to guix. I ran the following command, it produces a few false positives.

  grep define-public -R | sort | uniq -d

The following patches attempt to remove the duplicates, favouring the
original package definition.

Is there any way of guarding against adding these, or more accurately
checking for duplicate definitions?