If an Earth crashed into Earth at 12km/s and angle 15 degrees, you may have some survivors on the opposite side....
I think 12km/s is impossibly small for two earths colliding. With both objects being planet sized, they would both be strongly attracting each other, so you're dealing with two accelerations instead of one.
At any rate a grazing collision like that would probably cause so much momentum to be transfered or lost as collision energy, that the most of the remains of the grazing object would not achieve escape velocity and just impact again later on. The devestation would definitely be global for both worlds.
Also I said this before but people seemed to ignore it, so I'll say it again: the simulator at lpl isn't intended to be used with colliding planets and moons or other unusual objects and velocities. Beyond a certain point, the equations used in the simulator no longer accurately reflect what really happens in the impact. And for good reason, it just becomes way too complex to model this way.
