I found a glitch when you start a side mission of a taxi, cop car or a ambulance and start a replay with a rampage at the same time and then cancel the side mission you can go to the normal mission and still rampage is on then the cutscene of the mission start when you skip the cutscene and wait until the rampage is over you can second time go to the normal mission maker. So when you then finish the normal mission it will say you failed it but really the mission is complete.

I think you're talking about something like the Jury Fury dupe? If so, then that's already known. :P For Jury Fury you enter the marker once, wait until the rampage runs out (or complete it in 100%), and then you start the mission again which passes the mission after a few seconds.

oh ok Didn´t know it