Morrisons, Sainsbury's, Tesco and Asda have all been caught selling multi-packs at a lower unit price than individual bottles or cans.
The practice was outlawed in Scotland two years ago in a move to combat binge drinking, but remains legal in England.
Highland licensing standards officer Ian Cox said he regularly warned store managers about breaches.
He believes the problem lays with pricing policies being drawn up in England.
"It is not done deliberately but it certainly is a contravention to the existing regulations and it is an advisory issue," he said. "I come across this lots of times with Morrisons, Sainsbury's, Tesco and Asda.
"A lot of the pricing units of those big chains are south of the Border and it comes to Scotland. It's down to the wine and alcohol managers on the premises to pick up on it."
However, regional MSP John Finnie was concerned to learn the mistakes were happening repeatedly. Mr Finnie, a former police officer, was alerted to the practice by a constituent who sent photographs taken in Tesco stores at Inshes, Inverness, and Dingwall, apparently showing beer being sold more cheaply in a four-pack.
A Tesco spokesman admitted there was an issue with the Scottish beer product.
Morrisons said it was not aware of an issue as it had received no complaints in its Inverness store.
Asda and Sainsburys did not respond to requests for a comment.