why is it that when I use this website to search for backlinks to my site, I get listed EVERY blog post of one blog to which I only posted a backlink on only one of his blog posts? Yet it is showing that I have a backlink to all of his pages pretty much.
If you have done a link exchange then your link is visible in such a panel which appears with each and every blogpost. Say for example if you are having wordpress blog then it has a widget that shows added external links in right panel. So whenever a new blog post is being done the same panel appears and as the bot crawls the html it founds your link over there. If you have done blog commenting then surely the blog facilitate to show recent comments on the same right panel which appears in the same manner.
Yes,I agree with feelawake's point it happens when we post for a forum or a blog as a result we links more than that but I am also not too sure about the reason