Are what people call Onyx clowns actually different from Amphiprion percula, or just perculas that have a lot of black coloration on them?

Regardless of this, they are really cool looking, does anyone know where I can get a pair? Not necisarrily a mated pair, just two that get along.

Also, do they like bubble anemone's, or do they prefer something else....or is it just up to them with what they host?