The person who discovers the planet, shoudl choose a number from one to twenty six, each one will linked with a letter of the alphabet in no particular order. The said person must choose one of the numbers and is given the letter it corrisponds to. they must then flip a coin
Heads- A smart/sensible name
Tails- A rude/vulgar name
Furthermore, in the unlikely event of the coin landing on its side, the planet must be removed from existance to prevent further arguments of its name.
Im sure if we abide to these rules, all will be well.
Alternatively we could call them Earth.2, Earth.3, and so forth.