Shaw crashed his utility into two parked cars, returning a 0.14 blood alcohol reading when breath-tested by police at the scene.
Shaw denied Didak was a passenger in the car, with club president Eddie McGuire and skipper Scott Burns backing Shaw's version of events publicly.
But it emerged on Monday night that Didak was in fact in the car, with the club now deciding what action to take against the pair.
"The sanction imposed on Heath by the club on Monday was a result of information stated by both Heath and Alan after being repeatedly questioned about the incident," the Magpies said in a statement.
"Given the club has now found their information to be false, it strikes at the principles of honesty and integrity that the Collingwood Football Club is built on.
"For this reason, the sanction imposed will be immediately reviewed by the club, and media will be notified of a press conference to be held on Tuesday."
Shaw was facing a $10,000 fine from the club, though he was going to be allowed to play in Collingwood's important match against St Kilda on Saturday night – the Magpies keen to ensure Shaw faced the music publicly for his drink-driving shame.
But the latest twist and stunning turnaround is certain to put both players' careers on the line, especially after the club strenuously denied Didak's involvement.
Witnesses had said Didak was at the scene of Sunday night's crash.
But Shaw denied Didak, who was last year threatened with the sack over a night out with Melbourne CBD murderer Christopher Wayne Hudson, was in the car.
Shaw told a packed media conference he had simply called Didak, with whom he had been drinking, immediately after the crash, imploring him to help, and that Didak walked from the hotel to the scene.
"I rang him and then I saw him walking down and then, because there was a bit of a crowd around me, I just told him to go because I didn't really need him there at that point," Shaw said.
Collingwood president McGuire and skipper Burns also backed Didak publicly.
"Didak will be accused of the Kennedy shooting next," McGuire said when quizzed whether Didak had any involvement.
And when asked why he believed Shaw's story that Didak wasn't in the car, Burns said: "Because Heath said so.
"Heath has said that Alan was not in the car with him."
The incident has heaped further unnecessary pressure on the slumping Magpies, who are no strangers to drink-driving incidents among their players and have lost their past three matches to be in danger of dropping out of the top eight.
