Michael Schneider Variety Editor at LargeSPOILER ALERT: Do not read ahead if you have not watched Season 7, Episode 5, of “The Masked Singer,” “Masking For a Duel — Round 2,” which aired April 6 on Fox.That’s no illusion, it really was Vegas legends Penn and Teller unmasked on Wednesday night’s episode of “The Masked Singer.” Penn Jillette and his quiet partner Teller were disguised under the three-headed Hydra outfit.And yes, that was Teller who did most of the singing — in two different voices, one as himself and one in an aristocratic-style voice patterned after Rex Harrison in “My Fair Lady.” (As a matter of fact, the duo dubbed the voice “Rex.”)That may very well be the only time you’ll ever hear Teller — famously mute during all Penn & Teller appearances — actually talk. According to Jillette — who naturally spoke solo with Variety — the decision was made to have Teller sing most of the songs since Jillette’s booming voice is so recognizable.