WordPress SEO by Yoast plugin duplicates title tag on certain pages

version 1.1.2 of WordPress SEO by Yoast

on every page, the title of the page (what appears next to URL of page in browser) has some sort of duplication, depending on the page type.
on the home page of the site, the title is exactly doubled what it should be, with no space between the duplicates. on single posts within a category, the only thing that is doubled is my site name “Shayes Says”. On category pages, the same thing occurs. on single pages not categorized, the same thing occurs except there is one more “|” in between the page name and my name. check it out:

https://www.shayessays.com

using NomNom theme by Zeaks:
https://zeaks.org/nomnom-twenty-eleven-child-theme/