I feel you. Unfortunately this happened to me twice and I got a notice by Hubpages which said that I have copied someone's content! I was furious as you can imagine, because at least Hubpages saves the date you create the content for the first time and the date when you edited it last. I ran Copyscape and I found out two different bloggers who have copied part of my content. I asked them nicely to remove it. One of the bloggers did, because she didn't think it caused me problems. Anyway she deleted the post. The other one did not even reply! Because of him, I had to delete the whole hub! I was heartbroken to say the least, because that certain hub was even my very first hub I published on Hubpages!!
The process of proving which one of the posts [yours or the other blogger's] is the original, is too long and requires a lot of formalities. That caused me to delete my hub. I hope I won't have this problem again. I hope you will not have this problem ever!