It should choose the tasks at random. It can give the same one multiple times, but it's all randomized. There are destroy vehicle, kill HVT, destroy radio, or find intel, I think that's all of them. Each time you play it should pick randomly between those. If you don't like the ones it picked, you can always exit and re-run the mission to get a new selection.

Very, very good mod. But i've tried to have different tasks, but even if i selected 2 of them and choose 2 objective, the game give me 2 of them (the same type). Is there the possibility to do 2 or 3 different tasks, like e.g. 1) find intel 2)destroy something in the same game?