DuracellEnergizer said:

^That's part of the reason why I dislike the Rule of Two and -- by extension -- the modern incarnation of the Sith. The premise that they're so emotionally unstable and PURE EVUL that they'd wipe themselves out through infighting if there were more than two of them at a time is completely ludicrous.

The problem that I referred to was very much present before TPM was released. Vader and Palpatine beg Luke to try to kill them, Kun uses the dark side to kill Nadd, and Ulic uses the dark side to kill Satal.