This feature was 'fixed' by Frontier Development in a patch. It is kept here for historical reasons.

What makes this black hole system remarkable is the second planet: A gas giant with a pair of moons sharing an orbit. The B and C moons orbit so close that they appear to be on a collision course with each other! How the system stayed so long stable is not known. Based on calculations of orbital periods, explorers currently estimate the moons will be in collision proximity roughly once every 133 days.

Also it should be noted that landings are dangerous as there is a possibility of being crushed between two planetary bodies; due to the complicated gravitational effects that are in place, a ship's speed does not always match the orbital speed of the planets when exiting supercruise.

On 15/10/3303 a collection of explorers assembled in this system to witness and document the collision between these two objects. These moons appear to have collided and continued on in their orbits. Commanders reported a variety of gravitational issues and hazards, as well as incredible viewing opportunities. Video of the collision on this date can be seen here.

Link: Full Discovery Thread