All the references adding in this edit: https://en.wikipedia.org/w/index.php?title=User%3AThryduulf%2Fsandbox&diff=568232613&oldid=568231803 were added using the "use existing reference" option.
It seems that only when I added the same reference on the same line (trying to reproduce a different bug) did it reuse the existing ref rather than creating a duplicate one.
Version: unspecified
Severity: normal