There was queuing traffic on the northbound carriageway between junction 26 at Orrell and junction 27 at Standish after an accident involving three vehicles at 7.30am.
Traffic officers from Highways England arrived quickly and the cars were moved to the hard shoulder.
There were no injuries.
About an hour later, there was an eight-car shunt involving vehicles mostly in the outside lane, blocking lanes two and three.
There were no injuries, but there was damage to the front and rear of several cars.
The road was closed temporarily so the vehicles could be moved to the hard shoulder.
Most cars were moved within 30 minutes and the road was reopened by 9am, but lane three remained coned off until 10.30am when the remaining vehicles had been removed.