Javascript random names

Hi everyone, recently I started to improve my website’s (nerdologic.com) SEO and I noticed that I have to minify some javascript and css. The problem comes when I go to the minify section in the plugin I use (W3 Total Cache) and try to add some files. The format should be:

http://nerdologic.com/wp-includes/js/jquery/jquery.js?ver=1.11.3

But when I check up the site the testing tool tell me that I have to minify something like this:

http://nerdologic.com/wp-includes/js/jquery/jquery.js?7c5e85?ver=1.11.3

What is that “7c5e85?” part? It changes every now and then showing another characters. Please help me understand this madness! Thanks in advance