When adding new content through Content Sets we should have the option to add or to replace the existing content. Not sure if it is a bug or a misuse. Nevertheless just highlights the lack of clear instructions in how to use the Content Sets
Thank you for your feedback, I agree this area could be a lot clearer. I also agree there should be the option to add or replace the existing content as well.
I cannot say when this will get included however we will consider this for an upcoming version.