Charles Ludlam’s “The Mystery of Irma Vep,” the second production in the Bay Street Theatre’s summer Mainstage season, will open on Tuesday under the direction of Kenneth Elliott. The play was first performed by Mr. Ludlam’s Ridiculous Theatrical Company and proved so popular that it ran until April 1986. A two-person comedy, it will star Tom Aulino and David Greenspan, a five-time Obie Award winner.