[Evolution] Removing dupes

[Dan Jones <ddjones riddlemaster org>]

I recently went from Evolution 1.4 to 2.0.  Evolution 2 informed me that
the location where messages were stored was different and started
importing all of my old messages.  When it finished, it popped up a box
asking me whether it should delete or save the old messages.  I told it
to delete them and Evolution crashed.

I restarted it and it again informed me that the location was different
and started to import the messages.  Then it complained that the
directory it was trying to create already existed.  I told it to
overwrite the directory and it continued.  I got the same error several
more times.

This time, Evolution finished the import without crashing.  The problem
is that both imports worked - I now have two copies of every message in
my archives, which is close to 100MB of messages (now taking up almost
200MB.)  Is there any way or any tool to go through and weed out the
duplicate messages?