Can a black hole , eat another black hole ?

Black holes are the ultra-dense, ultra-compact, ultra-massive pits of overwhelming gravity that have a pull so strong that, for the most part, nothing can escape their grasp—not even light. When something comes within range of a black hole, whether it be a star, a cloud of gas or a truly unfortunate intergalactic traveler, that thing is stretched thin and ripped apart, atom by atom. So, the obvious follow-up question to all of this is: What happens when two black holes try to eat each other?

Universe Today knows: “The short answer? You get one super-SUPERmassive black hole.”

The longer answer, they say, is being worked out by a team of supercomputer-enabled scientists. When two super-massive black holes approach one another, the disks of orbiting gas and dust that surround them merge, creating a “towering vortex that extends high above the center of the accretion disk.”

The “towering vortex” identified in the simulation, says Bruno Giacomazzo in a NASA release, “is exactly the type of structure needed to drive the particle jets we see from the centers of black-hole-powered active galaxies.”

The merging process, NASA says, would kick out gravitational waves—distortions in the fabric of space-time that could be seen by satellites orbiting above the Earth. But, in order to see these potential gravitational waves, a finding that could help round out our understanding of many facets of the universe, scientists need to know what sort of sign to look for. Hence, the above computer simulation of two merging black holes.

Black holes exist only in somebody's imagination. The basis of the theory is an assumption that a body can collapse under its own gravitation. One exercise in PHYSICS 101 is to integrate the gravitation inside a sphere. If it is hollow there is no net gravitation anywhere inside. If it is solid then gravitation gets lower as you approach the center, and at the center it is zero. Isaac Newton was the first to point out these things. In real life gravitation depends a lot on the density of rocks and materials nearby, and also on centrifugal force as the body rotates. So the foundational assumption of the black hole is nonsense.
en.wikipedia.org/wiki/Shell_theorem

In Einstein's theory the gravitational field, manifest in the curvature of spacetime, is coupled to its sources by the field equations, the sources being described by an appropriate energy-momentum tensor, and so the Principle of Superposition does not apply. This means that one cannot simply pile up masses in any given spacetime because the field equations must be solved for each and every configuration of matter proposed.
(This paragraph was taken from news.yahoo.com/black-holes-may-supermassive-eating-stars-134604121.html but they deleted it from the article. Apparently somebody couldn't stand the implication of what it said.)
Second source: www.thunderbolts.info/wp/2012/08/16/a-blind-man-in-a-dark-room-looking-for-a-black-hole-that-isnt-there-2/

For the final nail in the theory, it depends heavily on the gravitational constant being constant, which it is not. It varies in the third decimal.
en.wikipedia.org/wiki/Gravitation_constant