Use the model to generate image variations, filter out things that look too similar to the original. Then you can replace the original art works in the training set. Also remove artist names from the text, you can later create new style IDs. This will make it harder to duplicate the exact expression of an original work but still learn the ideas and visual styles in a more abstracted way.

For all the non-problematic training images you can use the originals. Some artists might want their names to become popular as style keywords.