I've searched through all my Lees and I can't find any marrying a Gosnell twin unless Lawrence B. "Bub" Gosnell was a twin. I do have a sister Mary A. who I've noted as being born @1832. She died at age 6 from a spider bite. He was born 6 Sept 1832 on Lot 17, Ridge Rd., Orford, Kent Co., Ontario to John Joseph Gosnell and Sarah Reeder. On 6 Feb 1856 he married Sarah Lee, who was born 28 Dec 1835 in County Cork, Ireland to John Lee and Sarah Sheehan.
My only other Lee marrying a Gosnell is Thomas Lee, born 26 Mar 1841 in Ireland to John Lee and Mary?. He married Frances "Fanny" Gosnell, born 28 Mar 1844 in Orford to James Gosnell and Ann Gosnell, on 26 Nov 1864.
Are either of these likely? Where did you get your info? Who were the parents of your couple?