Duplicate content issues after conversion from Nucleus

Greetings,

We currently have many Nucleus blogs that we are converting to WP. In Nucleus, we do not have “fancy url’s” enabled, so they are indexed through Google as domain.com/blog/?itemid=###.

We’re trying to find out if once we enable permalinks in WP, if we will be penalized by Google for duplicate content.

Does anyone know the answer to this? 🙂

Thanks in advance!