in-text citation appears with a and b for the same reference

Hi, I have been using endnote for the same file for a long time. Now today suddenly it started making problems. I had lots of references in the file, now by adding the same reference letters ‘a’ and ‘b’ get added to the in-text citation and the reference appears twice in the end of the text. It seems that it reads new references with new codes.

HOw can I solve this problem?

you shouldn’t be editing your references to get the a and b but the style.  Editing the reference, changing the year has caused endnote to consider them “new” and the older ones are kept in the “travelling library” as different.  So first, delete the a and b from your records in the library, edit or choose a new style (or attach your style). 

To edit your style, in words, Edit> Edit Output Style> Edit “your current style” go to citations>Ambiguous Citations, and select “Add Letter after Year”  option.  Save the style (should use Save As, unless this is already a modified style) and give it a meaningful name. 

ambiguous citations.gif

I further edited that reply with some info on how to edit the style. Also, you will need to reinsert those manually altered altered year containing references.