Using an exported Endnote traveling library in an MS word document that has a pre-existing Endnote library already assigned

I tend to use accession number rather than record number in my temporary citations settings. (most of my records were downloaded from PubMed, and the accession number is included in the records). Then both libraries will match your inserted citations when you update citations and bibliography.  Otherwise, it will probably retain the “traveling library” version of the citation. I really try not to create a library specific to each paper though.