There are a number of look-alike clowns with two white bars. My initial impression is A. akindynos, but A. clarkii might be correct. I don't think they are A. sebae, as the rear bar is too upright. If I remember correctly, A. sebae tends to have dark pelvic fins too. The degree of extension of the posterior bar on to the dorsal fin is variable in the various species, and is usually more pronounced in juveniles (regardless of species). I'll take a better look tonight once I can get at my library. It would help to know the size of the fish.
Tony