YIWU, China, July 24 (UPI) -- Two identical couples who run a Yiwu, China, restaurant said they have been branded a "robot couple" by customers who cannot tell them apart.

The couples -- twin brothers married to twin sisters -- said customers are often dumbfounded to find the same faces opening the restaurant at 6 a.m. and closing at 3 a.m., The Telegraph reported Thursday.

"Many diners thought we worked too hard and are like robots, but they don't know that we are actually four people," said one of the twin brothers, Mao Zhanghua, 32.

Mao said both couples got married three years ago and the quartet decided to go into business together. The pairs also each have a young son, and they said the cousins are nearly identical.