mutual mystification 

During a act of cooperation, negotiation or decision making all parties withhold knowledge or information that either prolongs the process or completely destroys any chance of reaching the best possible result for all parties.

In order to "one up" the other both the sales and design teams created mutual mystification byfailing to disclose important exceptions and outlyers in their data that had the ability to compromise any final decision thusly

mutual mystification by Craig H. November 2, 2006