Bien bien

Bien, bien is often used with negative constructions to mean not very well.

• Lo conozco pero no bien, bien. I've met him but I don't know him that well. It's easy to imagine that you could use this example verbatim in real conversations.
• Pero bien, bien, no sé qué es una garnacha. I have only a vague idea of what a garnacha is. I don't know exactly.
• Bueno, así bien, bien, no sé a qué se dedica mi hermano. I don't know exactly what my brother does for a living. I only have a general idea.

Bien, bien is also heard as a reply to ¿Cómo estás? It's just part of the greeting ritual. — Bien, bien. ¿Y tú?

Recall that bien works informally for very. Es bien bonita. She's very pretty. So perhaps bien + bien is best understood as very + well.