In bug 50502 comment 7, Guillaume reported:
In this edit, a table was duplicated (but it wasn't in a template):
I was able to replicate this in Chrome. In addition, I was able to download the original Parsoid HTML for that old-id, the wikitext for that old-id, edit the HTML locally and verify the table duplication on the command line as follows.
$ node parse --html2wt --selser --oldhtmlfile /tmp/fr.html --oldtextfile /tmp/fr.orig.wt < /tmp/fr.edited.html > /tmp/fr.edited.wt