At New World, Vogel's, Ploughman's Bakery and Nature's Fresh loaves were on special 11 out of 12 weeks. At Pak'nSave Lower Hutt, Nature's Fresh bread had an "extra-low" price of $2.99 for all 12 weeks.
When the price of a product was regularly reduced, the special price is really its usual selling price, Duffy said.
"Many of the items we tracked were routinely discounted. While genuine price promotions are good for consumers, we found specials aren't always as 'special' as supermarkets would like us to believe," he said.
Stores enticing customers with price promotions must be offering a genuine deal. Otherwise, they'll mislead consumers and breach the Fair Trading Act, Consumer NZ said.
The organisation is calling for the Commerce Commission to investigate the industry.
"New Zealand has one of the most concentrated supermarket industries in the world, with two big players dominating the market. That degree of concentration brings with it the risk consumers will end up paying higher prices," Duffy said.