I found this strange problem in several articles recently translated with CX2 : ISBN are added twice to the translation, the fist one is correctly formatted with the {{ISBN}} template, the other is using [[Special:BookSources]] which should be avoided for readability.
Exampe on frwiki with [[ https://fr.wikipedia.org/w/index.php?title=Anarchisme_expropriateur&action=edit&oldid=156986859 | Anarchisme explorateur ]], but I saw the same problem on other articles by different users ([[ https://fr.wikipedia.org/w/index.php?title=HMS_Avon_Vale_(L06)&action=edit&oldid=156999116 | HMS Avon Vale (L06) ]], [[ https://fr.wikipedia.org/w/index.php?title=Toxophilus&action=edit&oldid=157010700 | Toxophilus ]]...) and only recently (at most a few weeks).
```
{{ISBN|987-580-092-9}} [[International Standard Book Number|ISBN]] [[Special:BookSources/987-580-092-9|987-580-092-9]]
```