multiple boards?

While I can see the benefit of being double boarded in related fields or fields that require previous training (ie, Gen Surg and Plastics) I cannot see any benefit for such disparate fields as Surg and Radiology. It might help you read films better as a surgeon, but that is hardly worth doing a residency in Rads and while Surg training would help you if you wanted to do Interventional Rads, again, it is probably not worth the extensive training which would not relate to your field.