Try it once by changing to the attached style which worked fine with a single author who published in the same year from my library . If that doesn’t work make sure the author field in the two references is exactly the same. Copy it from one and delete it from the other and paste in the copy.
Does it work now?
I have Endnote X7.7 and Word 365/2016 on a PC running Windows
Cell Copy.ens (12.9 KB)