I suspect this may be related to an existing bug, but if so I can't figure out how to find it.
Looking at the very bottom change on http://en.wikipedia.org/w/index.php?title=User:SLBohrman&diff=next&oldid=562259398, we see the first in a series of edits where editing elsewhere adds duplicated characters to a template that I don't believe is being edited directly. (Further duplication occurred in these edits to the same page: http://en.wikipedia.org/w/index.php?title=User:SLBohrman&diff=next&oldid=562359846, http://en.wikipedia.org/w/index.php?title=User:SLBohrman&diff=next&oldid=562363670, http://en.wikipedia.org/w/index.php?title=User:SLBohrman&diff=next&oldid=562363840)
Version: unspecified
Severity: major