Notes:

source

at least in Last Stand of the Wreckers.

Valder Farkill and Overlord are both members of a elite squad (Valder being credited with more kills than the entire squad combined). Both want to have a duel with their respective leaders (Treize khushrenada and megatron) enough to stage a coup in a remote area to provoke them into fighting him (remote colony MO-V and Garrus-9) and being distracted with the news of their rival/target's demise led to their defeat (a more permanent one in valder's case) and even then both heroes had to use unfair tactics to bring them down (using a performance booster/booby trapped).