I hope they don't compare us to see which one has held up best," said Abigail Van Buren, plumping her spray-stiff coiffure just in case. Ann Landers replied in the spirit of sisterly détente, "Let's hope nobody wants to know which one of us is which. We've been telling people that for 58 years." The rival grandes dames of advice-giving agreed, "We just want to go home as the Friedman twins."

Hand in hand, Ann and Abigail (born on July 4, 17 minutes apart) then deplaned from Ozark Airlines flight 989 into a battery of flashing Instamatics.

The Friedman twins—Esther Pauline (a/k/a Ann Landers) and Pauline Esther (Dear Abby)—had arrived home in Sioux City, Iowa for their class's 40th reunion at Central High School. Back then Esther was "Eppie" and Pauline was "Po-Po," and their friends still call them that. Po-Po is married to wealthy businessman Morton Phillips of Beverly Hills; Eppie, who lives in Chicago, is divorced.

"I stayed up all night studying the yearbook, and I wanna tell ya everyone in this room tonight looks a darn sight better than 40 years ago," Eppie told the reunion crowd.

But whatever four decades—and who knows what surgical legerdemain—have done to Sioux City's most famous alumnae, in some ways their lives have been little changed by the enormous success of their columns, which appear daily in 1,700 newspapers.

"We were unique in high school. We dressed alike. We looked alike. We were so used to being stared at that being celebrities has never seemed any different," the sisters explained.

Po-Po confessed that she and her sister sometimes attended each other's classes—depending on who had done the homework. Biology teacher R.D. Hissong, 88, admitted being taken in. But classmates recalled that violin teacher Leo Kuchinski had a fail-safe detection system: "He could tell from the first note." If the budding violinist sounded more like Jack Benny than Jascha Heifetz, it had to be Eppie.

The Friedman twins were dispensing useful information long before their pseudonyms became household words, their friends revealed. "When they told me babies came from between the mother's legs—why, I fell off the curb," claimed Rosanna Dikel Kornfeld. "They always knew everything first."

They still try to keep up with the times. Po-Po said, "Just recently I confided in Eppie that I'd seen an X-rated movie, and she admitted she'd been wanting to see it. 'But I was afraid I'd be recognized,' Eppie said. 'How did you get away with it?' I told her, 'Well, I just put on my dark glasses and my Ann Landers wig and went!' "

The hotel in Sioux City had given the sisters the bridal suite, two bedrooms separated by a parlor. But Po-Po disclosed that they shared the same king-size bed. "When we are together we still sleep curled up in each others' arms like we always did. We talk and laugh all night." So much for past rumors of jealousies and feuds between the columnists. (They even went to the ladies' room together on the Ozark DC-9.)

For the big reunion banquet at the Hilton Inn (neither smokes nor drinks), the sisters chose not to dress alike. Eppie-Ann swept to the head table in a stunning knit Adolpho cheongsam. Po-Po-Abby wore a silvery blue lame Molly Parnis. The couturial éclat of both creations may have been somewhat lost on school chums, many of whom acknowledged that their own gowns were off the rack at J. C. Penney.

The Friedman twins flew back to Chicago on Sunday in agreement on their answer to any letter from "Undecided" about his high school reunion. Should he attend? "Go!" they chorused. "It's like an extra facet on a diamond. It'll make all your memories even more precious."