Fashion Week ended on an embarrassing note for Trelise Cooper after a ribbon design on a grey sweater in her Summer 2010 collection was revealed to be identical to that on a jersey sold at a British chain store.

"It's devastating for this to happen," Cooper said.

In July, London-based designer Markus Lupfer released a grey jersey with the same red ribbon embroidery through Topshop.

Herald on Sunday gossip writer Rachel Glucina tried on the top during a London visit.

Today, she reveals the similarities between the two patterns.

Cooper said she had sourced the embroidery in April, then sent it and her sweater design to her knitwear supplier for production.

"I got the piece back in July - the same month it came out in Topshop."

Cooper said she had documentary proof of her chain of supply and timeline and that she had not seen Lupfer's design until approached after her show at Fashion Week. "I didn't even know it was in Topshop."

She said she suspected the supplier of the embroidery had sold it twice - to her and Lupfer.

Lupfer could not be reached for comment.

AUT University law professor Noel Cox, an intellectual property expert, said the issue raised thorny questions of copyright because the two garments look "virtually identical".

"The primary artistic element of the piece is the ribbon - and that's very similar," said Cox.

He said fashion designers were extended the same protection under copyright law as authors, musicians and artists.

"Fashion is a form of intellectual property, and is no different from a book or a work of art."

Cox said a party could launch breach of copyright action over the affair but any financial compensation would be minimal. He added that the real damages would be done to reputations.

Cooper said she would be approaching the supplier of the ribbon embroidery with a stern message not to double-sell.

"Don't do this to me! We have mean media in New Zealand who point this out."

Despite the controversy, Cooper says the garment is selling well.

"My customers love the piece."

In 2005 Trelise Cooper accused Arrowtown accessories designer Tamsin Cooper of a breach of copyright and sought to reserve the brand name "Cooper" for herself.

The matter was settled out of court after a 20-month legal wrangle.

On this latest tangle, Tamsin Cooper said: "I'd love to comment, but I really can't."