I often place symbols from my common library in my current document & get this warning "One or more library items already exist in the document." I never want to replace them, so I wish I could tell it once & for all and it would stop asking.
I know that if I take symbols from my document library it won't give me this warning, but that's not where I like to get them. In the document library symbols are not categorized in the folders like they are in my common libary. It's easier to find them in the folders than all on one level.