Italian clothing marketer Benetton has again created controversial advertising. This time it is a poster in Europe showing a black stallion mounting a white mare. Two of the biggest outdoor board contractors in Europe have banned the ad from all their sites. French group Avenir and British contractor Mills & Allen have turned down the ad on moral grounds. The posters will appear in Denmark, Norway and on a few sites in Belgium next week. Benetton is preparing a substitute ad for the U.K., to appear during September on boards and in magazines. Zoe Brown, a spokeswoman for Benetton's British office, said the two-horses ad has provoked more initial outcry than such other Benetton shockers as the picture of a dying AIDS patient, a human heart and a black woman breastfeeding a white baby. Benetton ads are created in-house by Olivireo Toscani.