Different channels are used for intellectual property protection in commercial and legal domains. Historically, copyright has been used to protect works of art. You can't make a copy of an art work without permission. However, it's usually okay to take a photo of a status, or draw a model, even if the same person has been used by another artist with same clothes in same gesture.
Artist who made the iconic campaign poster of Senator Obama lost in a case when AP complained an AP picture was used to produce the poster. However, he lost because 1) the Black&Red poster was actually produced in Photoshop with the original AP photo; 2) he lied about it in the early stage of the trail.
Usually When an art work is found similar to another one, unless it's an exact copy, there's not much to say or to do. One well accepted principle is that you can't 'patent' an idea or a thought. The successfulness of an art piece is determined by the target, the method and the execution.