Ok, now I understand.
Is that first set of keywords generated by Joomla or is it part of your template? Are you using some other component that works with keywords.
JoomSEF should append the keywords from it to your existing ones. It should not add any extra tag if it already exists. However, it only counts with the Joomla standard, so theoretically, there could be some incompatibility if you use some 3rd party component.
What you may try to do is to disable the JoomSEF metabot in your mambots list. If the extra tag disappears after you unpublish it, then it was probably caused by JoomSEF and we may check the reasons of that further.
Please, do this test and let us know.
Best regards,
ARTIO Support Team