Mary-Kate and Ashley Olsen were twinning (of course) at the Met Gala

The Met Gala allows celebrities to add their own flair and interpretation to the year's theme, or ignore them entirely. Mary-Kate and Ashley Olsen have always been in the latter "camp."

The former child stars-turned-fashion designers appeared Monday night at the New York City gala wearing full-length black leather ensembles, each embellished with gold buttons. The pair came as close as they ever have to a set of twins intentionally dressed alike.

"Camp: Notes on Fashion" was the evening's theme, but the sisters were anything but campy. Mary-Kate wore a buttoned-down jacket on top of a maxi skirt, while Ashley donned a long coat dress with a flash of gold that peeked out beneath the sleeves and from her skirt lining.

Held as a fundraiser at the Metropolitan Museum of Art in New York City, the gala celebrates the latest exhibit at the Costume Institute wing of the museum. Stars strut their stuff on the famous stairs of the New York institution to show off their (or their designers) interpretations of the theme.

The 32-year-old Olsen sisters tend to eschew each year's theme and the idea of being told how to dress at the annual event, where they have been a mainstay for years.

"We’re going to surprise everyone, " Mary-Kate told The Hollywood Reporter ahead of this year's fundraiser. "We always do our own thing anyway," Ashley added.

Last year, the twin sisters gave a rare interview to promote the launch of the first menswear collection by their fashion label, The Row. They described details of their close relationship, which Ashley compared to "a marriage and a partnership."

"It's been 32 years of learning to communicate," she said. "We have had ups and downs."

Yet, she said the pair do "everything together. "

"We came out of the womb doing that," Mary-Kate agreed.

The pair rose to fame after they were hired as toddlers to share the role of Michelle, the youngest member on "Full House."

They remained with the show from 1987-95, eventually starring in numerous TV movies.

The sisters eventually grew up to become businesswomen in the fashion industry. In 2017, the twins were said to have a net worth of $400 million.