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Since “Mad Men” made its debut on the AMC cable channel in 2007, BBDO has been mentioned in many episodes. But during the most recent season, the fourth, which concluded on Oct. 17, BBDO figured in one of the most significant plot lines, when it picked up the Lucky Strike cigarette account in 1965 from Sterling Cooper Draper Pryce, the fledgling agency run by the principal “Mad Men” characters.

“The unintended and unsponsored ‘product placement’ appears to have generated some increased awareness” for BBDO, Andrew Robertson, chief executive at BBDO Worldwide in New York, a division of the Omnicom Group, wrote in an e-mail.