Two alphabets

Dear Endnote users,

I’m having a wee bit of trouble with my references in Word (2016). They have sorted themselves beautifully by alphabet until about halfway down, and then the alphabet starts again. So we get from B all the way to R, and then it starts again at C - Y. I also have a lot of duplicated references. I’ve tried updated the citations and bibliography, but nothing changes.

Could this be because I have used two libraries?