Hypersmurf
Moderatarrrrh...
In any case the language seems to indicate that the spell only works for the caster.
That has nothing to do with whether you can have two running or not.
Even with Range:Touch the spell is targeted on someone.
No, it's not. It's an Effect.
If the Shield spell was "Effect: One disk of force", you could cast two and cover front and back at the same time. The reason you can't is that it's "Target: You".
Flame Blade has no target. It's an Evocation that produces an Effect, like Wall of Force. You can cast two Walls of Force at the same time; you can cast two Flame Blades at the same time.
-Hyp.