I occasionally book conflicting segments because I genuinely don't know which one I am going to fly and would like the chance to get at least an okay seat (aisle) and it's often better from a cost perspective to book 8 days in advance and pay a change fee then wait until 3 days in advance. I've never had an issue with this, but YMMV. These are generally corporate bookings so not sure if that makes any difference in terms of how they handle them.