Daniel Grant explores the legal framework around artists who copy the work of other artists revealing this interesting wrinkle:

There is recourse to the law when the distinctive “feel” of an artist’s work — the totality of its style, handling of paint, subject matter, color, use of light and perspective (none of which are in themselves copyrightable) — is copied, causing collectors to be uncertain about which artist did which work. This is a subcategory of trademark law, referred to in legal parlance as “trade dress,” in which the look or feel of the artwork is strongly identified with a particular artist. Performers Bette Midler and Tom Waits successfully have sued companies that advertised products using unseen singers in commercials who sound remarkably like them, and fine artists Itzchak Tarkay, Paul Wegner and Howard Behrens have also prevailed in legal actions against other painters who have imitated the elements that make their work unique. The courts apply two main tests for trademark cases in determining whether or not one artist may have stylistically copied another: The first is establishing that the allegedly copied work is identified by the public with the particular artist (in legal parlance, the art has acquired a “secondary meaning”); the second is proving that the imitation is likely to cause confusion in the market. “What better for showing probable confusion than actual confusion?” Joshua Kaufman, a Washington, D.C. lawyer who represented Paul Wegner, said. “Within a span of one week, Wegner received calls from three of his collectors who asked him, ‘What happened to your work? It looks like it deteriorated.’ They had seen imitations of Wegner’s work from a distance and just assumed it was Wegner’s. That can affect an artist’s reputation as well as sales, if people think the quality has gone downhill.”

If Works of Art Are “Strikingly Similar,’ Is That a Problem? (Huffington Post)