"The Dublin Core is a metadata standard for describing digital objects (including webpages) to enhance visibility, accessibility and interoperability, often encoded in XML."
see http://en.wikipedia.org/wiki/Dublin_core

AFAIK the DC meta tags are not used by any search engine.

Repeating your meta tags will
- make your site invalid according to W3C specs
- confuse spiders
- look spammy

faglork