CHICAGO – It took her a couple years, but small business owner Melanie Mann is glad she registered her company logo with the U.S. Patent and Trademark Office.

Mann, who co-owns Baby Swank, a Wilmington, N.C., seller of bedding, furniture and novelty items for children’s rooms with partner Jamie Mayo, waited two years before registering her distinctive logo that incorporates a baby’s bottom. Just two months after getting clearance, Mann received an unexpected solicitation from a children’s retailer in Virginia with a logo strikingly familiar to her own.

“I was just shocked,” said Mann, 33, who initially became aware of the rip-off after she received a promotional…