Could this bug be responsible for these edits where one templates was duplicated and the other apparently duplicated and substed in the middle of a category link?

https://en.wikipedia.org/w/index.php?title=Ford_Figo&diff=566719977&oldid=566176664
https://en.wikipedia.org/w/index.php?title=Ford_Figo&diff=next&oldid=566719977

This looks like the same issue, yes.

en.wp user reports that adding a single hyphen to a page trigged this bug to remove part of an infbox and duplicate other templates in the middle of a category.

https://en.wikipedia.org/w/index.php?title=IBM_Personal_Computer&diff=567356453&oldid=566275349

I think this diff from fr.wp is another example?
https://fr.wikipedia.org/w/index.php?title=Gen%C3%A8ve&diff=95604102&oldid=95601955

(In reply to comment #3)

en.wp user reports that adding a single hyphen to a page trigged this bug to
remove part of an infbox and duplicate other templates in the middle of a
category.

https://en.wikipedia.org/w/index.
php?title=IBM_Personal_Computer&diff=567356453&oldid=566275349

The table at the end was not closed. I [https://en.wikipedia.org/w/index.php?title=IBM_Personal_Computer&diff=567437920&oldid=567357722 fixed it (for consistency's sake, I used the s-end template)] and VE edits and saves should not introduce dupes on this.

Can someone check and see if https://bugzilla.wikimedia.org/show_bug.cgi?id=52618 should better be marked as a duplicate of this? Thanks!

In this edit, a table was duplicated (but it wasn't in a template):

https://fr.wikipedia.org/w/index.php?&diff=96159772

Is it the same issue or should I open a separate bug report?

Guillaume: This is a Parsoid bug (which I was able to reproduce). This current bug seems like a generic placeholder bug. I created bug 53429 in parsoid so we can identify more specifically what went wrong. You can add yourself to that bug if you wish.

I *believe* that this is now fixed - marking as such. Please re-open if you find it happening again.