Omnicom Group, New York, reported net income for the second quarter of 1996 at $53 million, up 22% over a year ago. Worldwide revenues from commission and fee income increased 17% to $666.5 million. Domestic income increased 26% to $353 million; international income was up 8% to $313.5 million. For the first six months, net income increased 22% to $83.9 million. The results include those of Ketchum Communications Holdings, recently acquired by Omnicom.