When Lister and Kryten developed the triplicator to increase their supplies, they accidently copied the entire ship and then caused it to explode. Two versions of Red Dwarf were created and the Dwarfers had to seek out whichever ship was the superior, so that they could find a working triplicator and reverse the procedure. They only had an hour to do this, as that was how long triplicated material could exist before disintegrating.
The first ship the original crew visited aboard Starbug was the "High" version. It was obvious that this was the better vessel, as everything about it was of greater quality. The rooms and corridors were clean and tidy, the air was pure and there was peaceful, relaxing music being played through the ship's PA system.
Lister decided to see what the food was like aboard this divine ship. He used a vending machine to order the ultimate test: A Pot Noodle. He and The Cat tasted it and declared it to be "edible", something Lister had never believed possible.
The inhabitants of this version of Red Dwarf were also superior, devoting themselves to lives of peace and spirituality. Rimmer declared them to be hippies and The Cat found his other self annoyingly pious and badly dressed. Kryten explained that they were smarter than the originals because they could access all of the knowledge that their predecessors had obtained throughout their lives. When they received a distress call from the other vessel, the Highs insisted on joining the Dwarfers as they searched for the other half of the triplicator.
When the Dwarfers and their higher selves travelled to the "Low" Red Dwarf, the Highs were rapidly killed by their "Low" counterparts, due largely to their excessive zeal in trying to find the good in their dark equivalents. Their vessel ceased to exist when Kryten amalgamated it with the low ship and recreated the original (RD: Demons & Angels).