Over my years of golfing southern courses I have noted many mature double/triple trunked live oaks. Usually developers treat these beauties with respect leaving them room to exist in their surroundings, each one having its own 'personality' to be admired.

Also noted, those with multiple trunks sometimes due to storm damage, weight of top growth or insect damage split in the middle and one trunk will break off, falling to the ground. The remaining upright trunk will heal itself and keep on growing. I had the opportunity to watch two ancient live oaks go through this healing process for about ten years. Both trees are still alive and growing well. Don't think this comment answers the question asked. OP will have to decide how he wishes to grow his tree.

Some of the really big ones have a split trunk.

I have seen so many pics of live oaks. Those that have the most trunks are Q. Fusiformis, but I was wondering about the hybrids I have. I probably shouldn't prune much until they get some size to them anyway. Maybe let it keep the trunk branches and maintain 1 leader til it gets 7-8 ft tall. I know Live oaks have several main/large branches in maturity, but some maintain one trunk until they are 35-40 ft tall, then the branches do their spreading out like witches fingers.