Course it's possible, my dad's work uses it, they split connections between 2 Fiber lines and a backup Microwave Dish.
It's possible yes, with expensive technology, with two phones talking to each other over an Ad-Hoc network, you probably wont get the best result and probably wouldn't be worth the trouble.
I'm pretty sure the 2 fiber lines are split like, half the building is on one line, and the other half is on the other. Not like both lines go straight into your dad's workstation at the same time.