Yep so after buying a full kit, i.e. 1 Smoke, 1 Molly, 1 Flash and 1 HE. You weren't able to buy the second flash before, right?
Now you can basically drop your HE to the ground and buy that second flash. That HE can be picked up by a teammate, you can juggle it along with you or you can leave it there, and someone will be able to pick it up mid-rotation. If all 5 teammates do this, it's literally possible to throw every nade once again.