Keyword sort produces duplicate keyword groupings

When sorting by keyword, it displays nodes grouped by keyword, as it should, except many categories will show up multiple times. They're also not sorted by any discernible criteria.

As you can see from the screenshot below, duplicate nodes don't show up, just duplicate keyword groups. For example, we see the "injection" keyword three times in the screenshot, but each injection group has different nodes. When I look at the list of keywords in the Biblio settings, it does not show a duplicate of any keyword.

This is currently available at http://65.60.42.146/~sludges1/research-library?s=keyword&o=asc