Copyscape says I'm a copycat

I recently did a Google search on a particular keyword phrase that ranks high for one of my sites and found out that there were other websites that had the same article published and in exactly the same manner, word for word. I then proceeded to using copyscape to find out how many of such copycat sites were republishing my article. I did this by entering the article url at copyscape.com and searched. To my surprise, there were no sites listed and I then proceeded to check the copycat site's url that copied the content from my site using copyscape and was almost bursting into laughter when I saw my site listed as one of the copycat sites.

Is copyscape's algorithm really working well at all? I've been using them for quite some time in the past and they've been effective but it seems that some websites have a way of hacking into their algorithm to make them list old urls as copycat sites while new urls are taken as original sites.

I just do hope that Google doesn't rank that website higher than mine in search results since my site was indexed before the actual copycat site.