A controversial Big Bash League (BBL) rule came under the spotlight during Saturday's Melbourne derby when two batsmen were each awarded six runs after hitting the roof when they could have been out caught instead.

The Renegades beat the Stars by six runs in a tense derby at the Marvel Stadium but the chasing team were let off twice when Joe Clarke and Beau Webster hit the roof and saw the ball land inside the 30-yard circle.

Under BBL rules, a ball that hits any part of a stadium's roof structure is scored as a six, leading many to call for the reintroduction of the old rule where it would be adjudged a dead ball instead.

Renegades bowler Will Sutherland, who conceded the first 'six', told cricket.com.au that the rule should be scrapped.

"Definitely can it after they had two go their way. I let out a few expletives," he said.

"It was even for both sides but I'd like to think it would be a dead ball going forward."

The rule initially considered only the fixed beams of the roof and not the retractable sections, which Renegades skipper Aaron Finch said was "hard to police", before it was changed to include the whole roof.

"You've got these beams that hang over, they're already over the boundary so if it hits that you should get six. If you hit it straight up and get six - honestly, I don't know," he said.

Stars skipper Adam Zampa said the rule was "bizarre".

"As a bowler you expect to deceive a batsman and at least be in with a chance of getting a wicket," Zampa said.

"Maybe build the roof a bit higher."