I am puzzled why it was created and altered all inside the very same second.  That's actually not easy to carry off--it's possible but not so likely.

Perhaps if the PDF file content was actually 'imported' from an older file into a fresh 'new' document (the new one having the exact file stamp we noted above), and saved that same second, it could have had the very same Create and Modify time.  

Or it might have been created by a conversion program that takes another kind of file and outputs the PDF file.  

Either way, there may be some forensic fun to track down 'prior versions'.