I found Terry's reference in ORN 20, and it was definitely Oliver Semmes that was on the Diana. He relieved another artillery office who had been in charge. (Don't have the book with me now, so can't give page numbers.) The Yankees were confused, too, in one message David Porter seems to think that it was Raphael Semmes working in the area, and he was concerned about it.

The Queen of the West was lost on April 14, and that was in a totally different action from the one in which Diana was involved. The Diana was in Bayou Teche fighting soldiers coming up the bayou; the Queen was over in Grand Lake, a wide area in the Atchafalaya River, tangling with US gunboats (Calhoun, Estrella, and others).