add check for matching existing before adding new statement
add check for matching existing before adding new statement

jonphipps/Metadata-Registry,jonphipps/Metadata-Registry,jonphipps/Metadata-Registry,jonphipps/Metadata-Registry,jonphipps/Metadata-Registry,jonphipps/Metadata-Registry,jonphipps/Metadata-Registry,jonphipps/Metadata-Registry,jonphipps/Metadata-Registry,jonphipps/Metadata-Registry