I've been experimenting again.

It turns out that when you're in a taxi, and the dude on the radio offers for a ride, it's the perfect setup. Here's the steps I found out so far:

1. Get a taxi (I used Franklin)
2. Pick up phone, and pull up a contact 2.5. Wait for taxi guy to offer a pickup
3. Start phonecall but also do next step almost instantaneously) 3.5. Accept the pickup (continue to hold until phone convo is over) ??????? there is no step 4, I haven't figured it out yet.

its happening...Kappa

Just some clarification here for those with their hopes up: IV uses a system way better than one single variable that says if you can start missions. Glitching that variable does not allow starting multple story missions in that game. It is unlikely that V would take a step back from IV's system.

I think "duping" in a GTA game is the general abuse of the mission flags.

Duping implies duplicating something, in GTA III, VC, SA and LCS you can duplicate missions by starting missions during missions (the same mission or not, it results in double the instances of the last mission triggered)

"Duping" in GTA IV is just a different glitch that abuses the same kind of mechanics to manipulate the onmission flag.

Why are we arguing semantics anyway?

When's video

Whenever I can figure out how to make a taxi explode at the same time and range it takes to activate the mission. Rockstar put an additional chunk of code that disables mission markers at a certain point Kappa

Duping in GTA V Soon that will be epic