EndNote users often report a problem where citations in their document have shifted up one position, to the location where the previous reference was cited.

There are various factors which may cause this problem: see the relevant FAQ on the EndNote website.

Every EndNote citation in your Word document includes a large number of field codes which you cannot see. The grey text that you can see when you click on a citation alerts you to the presence of the field codes. These field codes can easily become corrupted.

It is essential to use the EndNote Edit Citations command whenever you want to delete, move or merge citations. Use the Edit Citations command to delete the citations, and then reinsert them in the required position. Never use the delete or backspace keys to remove citations, and never cut and paste citations to move them to another position.

If your citations have shifted in the document, then the document has probably become corrupted. The best solution seems to be to unformat the citations and remove any field codes, and then copy and paste the text into a new document, which you can then format. See the FAQ on cleaning up field codes on the EndNote website.