Fun Fact: Oscar Wilde was not the originator of the first half of this quote. He did add the bit about mediocrity, though. I always thought this was quite the burn.
An artist friend of mine recently sent me an image of a post another artist posted on their social media of a couple different pieces that were extremely similar to my friend's work. No, they weren't exact copies of any specific pieces, but they were distinctly my friend's style, palette and compositions. The sting, I think, is that they know each other.
The first half of Wilde's quote, the original proverb, was the first thing I said to my friend in hopes to lessen the frustration and insult she felt. But, I think the second half is more important for the other artist:
Don't be mediocre. Be the great one.
I'm not going to get into the whole copyright infringement issue in this post. That's a beast in and of itself. I do want to talk about being your own artist and finding your own style. Yes, artists out there paint in the style of Impressionism, Realism, Post-Impressionism, Cubism, on and on. There's a difference between influence and copy. But, a Hirst is a Hirst, a Slonem is a Slonem. Do start carving up sharks or doing quick paints of bunnies and call it your own.
Another impressionist-style artist friend of mine took a private class from an abstract artist and walked away enriched from the experience. She didn't turn into an abstract artist, but she did incorporate different tricks and tools to create pattern and texture.
I always encourage artists that are learning their craft to take workshops and classes from other artists. These opportunities, though, are to walk away with nuggets of information and different ways that artist creates.
Find the inspiration of who you admire and see how you can apply it to your work... but don't copy.
(How did my friend handle it, you may be curious? She was the bigger person. She left it be and moved on, knowing that she has established herself and her work to be something not only sought after by collectors but by artists as well.)