If a paragraph contains a template, and VisualEditor is used to insert two characters somewhere after the template, and the second character is deleted with backspace, then the first character will be replaced by another character that is duplicated from several positions before that character.
To reproduce, go to
https://en.wikipedia.org/w/index.php?title=User:AxelBoldt/Sandbox&oldid=618813650&veaction=edit
and change the word "Italian" in the first sentence to "Itaxxlian", then delete the second x. Result: "Itatlian", where the second "t" results from duplication of the first "t".
This is a consequence of the IPA template earlier in the paragraph. The test file also contains a paragraph without template, where the bug does not occur, and a paragraph with a convert template, where the bug does occur.
Wikipedia is at MW 1.24wmf15 and I'm on Windows 7 running Chrome 36.0.1985.125 m.
Version: unspecified
Severity: normal