I recently read a post written by a blogger who was very distressed by the fact that someone had been imitating her blog. I can understand the frustrations of people stealing posts, techniques and pretending like it was their idea without attribution to the creator. It's a good case of plagiarism and even more irritating if they get more comments on "your stuff" than you did. Lol!
However, another way to look at it is this - you have just inspired another artist; original or not.
If there are copyright violations by all means take action but don't let it get to you. No one is quite like you, no one creates like you. God has given everyone the ability to create, Him being the Master Creative Director and all. He created everything, including you. You have the ability to create, so create! No two people can create the same way; find your edge and capitalize.