Stores selling gowns in the lead-up to school ball season are keeping a register of who's wearing what - to save girls the embarrassment of wearing the same dress.
As soon as a certain style has sold, the dress and intended event is recorded and no one else from the same school can buy that dress.
The trend has ruffled the feathers of a few who have missed out but the majority of girls - who fork out upward of $1000 for a dress and accessories - are relieved they will be the only belle at the ball in that dress.
Melodie Joseph from Modes in Newmarket said most were happy with the register."As a woman you don't want to turn up and see someone else wearing the same dress," she said.
The store had seen tears from girls disappointed they didn't get their first choice but who understood once it was explained.
Mrs Joseph said girls were already coming in to try on dresses even though ball season was three months away.
"We say to them to get in early and when they find the dress they love, to buy it, so they don't miss out."
Karen van Gysen from specialty store Bridal and Ball also had a register and extended it to red-carpet events such as the Halberg Awards.
"We have a lot of one-off designs from Istanbul and New York but there are others that we have more than one," van Gysen said.
"You can never promise that no one else will buy that dress elsewhere, but we do our best to make sure each girl has a unique look."
Ballgoers have also set up Facebook pages where photos of dresses can be posted so there are no double-ups.
Last year seniors at Whangaparaoa College set up an online ball-dress register so there was no risk of turning up in the same dress.
Former pupil Amy Johnston said the page was effective as many girls bought dresses at popular online sites so there was an increased chance of turning up in the same dress.
"All the girls that were attending the ball were invited to join the page so we could all post pictures of the dress we were wearing so people wouldn't get the same," Johnston said.
But some stores have chosen not to have a register, saying they cause more problems than they solve.
Charone Mackessack from Glamour Boutique in Newmarket said they had a register but then fielded calls from "cross mums" who were annoyed their daughter was prevented from buying a certain dress.
"We found it was impossible to ensure another girl wouldn't buy the same dress elsewhere or online anyway," Mackessack said.
"The same dress looks completely different on each girl so as long as it is not their best friend wearing it, it is not a big deal."