That item is in my registry also, though there is no blank item showing in msconfig.
It is just a "placeholder" in case there are no entry-names under the key.
Compare to:
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce and HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnceEX
It would serve no purpose listed in Startup Manager, in my opinion.
You might try unchecking it in msconfig. Maybe it will drop from a subsequent msconfig list.