[_nub3]

Actually it is explainable. This pitty comparison only tries to conceptually illustrate what is happening.

Think of a pond with a smooth undisturbed surface. Now, define two spots as center, and for each spot in the exact same distance a point of measurement.

Here it comes: now drop two identical balls of steel into the pond at the very same time and do your measurement. You will detect that the waves on the surface of the pond are perfectly the same.

The entanglement is - simply spoken - just a syncronizing of the particles, hence the reason why they "seem" to behave the same.