There is no check whether an id of a modulepropertytype is already in use
-> When creating a new modulepropertytype or when renaming an existing one, the check has to search for existing modulepropertytype with the same name. If one exists, the new name is extended by a running number. e. g. "Author1". Additionaly, an infobox should inform the user "renamed modulepropertytype to X because Y already exists"
Diff:
Ok! (Solved with autorenaming, e. g. when "interface" already exists, the new name is "interface1")