Adding pages to a PDF which have annotations with same author (title) adds a _# to the end of the author?

I have multiple single pages which have annotations from the same author. I use the title property to set this. When I merge the pages together the author of the annotation on subsequent pages gets a _# appended to it. For example, page 1 will be "Joe User", page 2 will be "Joe User_1", page 3 will be "Joe User_2", etc...