Year appears double in reference list, only in some references


I am using a journal specific output style. In some references in my list, the year appears twice.

The normal format is: Author, Title, Year.

The wrong format is: Author, Title, Year, Year.

In the library, the year appears only once in the field “Year”.

Does anyone have a clue why this is and how to fix it?

I am using Endnote X7 on Windows 8 and Word 2013.

Thank you very much!

Does it happen with other output styles?  If not, please zip the output style and attach to a comment.