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After four seasons of side-by-side crime fighting, it's clear that Castle and Beckett have come to know one another like the back of their hand, but how well does their knowledge stand up in real life? 

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Brooke Anderson of The Insider stopped by the set to test Nathan Fillion and Stana Katic on their co-star know how, and you might be surprised how two stand up in our Q&A.

Does Nathan know which James Bond movie Stana appeared in?

Can Stana remember Nathan's pre-acting ambition?

MORE: Double Take! Stana Katic and Mischa Barton

Test your knowledge along with the Castle stars to see how well you rack up in the quiz!

Don't miss an all-new Castle, tonight on ABC.