It wasn’t until late in their cabaret show Saturday at the Maine Center for the Arts in Orono that Ann Hampton Callaway and Liz Callaway sang segments of “Bosom Buddies” (from the musical “Mame”), “Together” (“Gypsy”) and “The Stepsister’s Lament” (“Cinderella”). One suspects the DNA-indebted duo decided the tunes would be too obvious, too corny for a show meant to highlight their considerable vocal talents as well as showcase them as a sister act.

But the truth is: Audiences would be happy listening to these two women sing from the phone book.

Liz’s voice has the sparkle of Broadway, and Ann’s has the candlelight of a piano bar buried deep in a city block. The combination was a match made in – well – Chicago. But where’s there’s a will, the sisters like to croon, there’s a Callaway, and these talented sibs proved their place in the musical annals of family combos.

A hybrid of the Callaways’ custom-made “Sibling Revelry” show from nine years ago and the more recent “Relative Harmony,” Saturday’s performance featured each of the sisters at her prodigious best.

With the additional hotshot duo of musical director Alex Rybeck on piano and Mark Minkler on bass, the sisters pulled from a range of genres including musicals, jazz, pop and original numbers: “It’s Today,” “Our Time,” “Friendship,” “I Know Him So Well” (“Chess”), a powerful rendition of “Stormy Weather” and the bebop classic “Cloudburst.” Most popularly received by the scantily filled auditorium was the theme from TV’s “The Nanny,” which Ann wrote and they both recorded for the show’s opening.

Liz is to composer Stephen Schwartz what Bernadette Peters is to Stephen Sondheim, and the payoff for audiences was a lilting “Meadowlark” (from Schwartz’s “The Baker’s Wife”). And only someone who played Grizabella from “Cats” for five years on Broadway could get away with singing “Memory,” which she did with measured and crystalline style.

In complementary shades of richness, Ann gave robust and athletic readings of “My Buddy/Old Friend,” “Rhythm in My Nursery Rhymes” and “Some People.” Her particular gift for scat, which she employs fluently, is only one component of an orchestral-sized agility.

A wrenching version of Carly Simon’s hit “That’s the Way I’ve Always Heard It Should Be” (with lyrics by Jacob Brackman) contributed a more serious note to the show. It was a welcome change from the sisterly bits that filled the spaces between numbers – and sometimes during them. Why two singers of considerable success would have to continue to underscore their accomplishments with silly onstage antics is a curiosity.

But the conceit of rivalry was easy enough to sit through because the music, star-studded and vibrant, was like a two-hour dream of a night on the town.