Everything has been done before.
Fayum mummy portraits exhibited tendencies toward naturalism long before the byzantine era gave way to the beautiful naturalistic portraits of the renaissance. Did Titian, Rafael, or Hans Holbein ever see these portraits? As far as I know, there is no writing that could reflect this, but the two eras certainly show more similarities than the flat art in between. Countless, nearly infinite versions of the lake, boat, and mountain as a landscape combination have been rendered. Christian religious subject matter has had it's share of copies as well. Baby Jesus, dying Jesus, ascending Jesus, etc.
The interesting thing about theme replication in art, for me the strongest example being seen in painting, is that it doesn't get old. Often, it is a delight to see many paintings created within the same vein. The spread of ideas has not caused a boring uniformity, but a flux on the original idea.
This is puzzling and exciting for me because something I have often worried about is how close I come to replicating the ideas of others. The need to be original pervades artistic culture, and creative culture in general. Yes, there is a point at which one can copy incorrectly, unknowingly with little acknowledgement or awareness of the original subject matter, a sort of "uncanny valley" in plagiarism. As Warhol might show us, conscious, overzealous copying can be portrayed as a commentary on consumerist culture. But even on the other side of this valley, slightly different portrayals of the same subject yield entirely different results based on the style and emotional response achieved by each individual artist.
It's a wonderful display of human individualism for this to be the reality. I can paint a house in the woods, and no one will compare it with the hundreds of houses and woods which have made their way into my subconscious to help me create that piece. My own strokes and colors, my own interpretation of the same idea, gives the visual representation a unique register.
So go out there, paint what you want. If it's in style, great. If it's out of style, people might care even more.
After all, someone has to bring about the next big rococo fad.