Can I kill both Mick Zaford and Jimbo Hodunk in same playthrough?
Solution 1:
No, Just like many other quests in the game, there are two possible rewards and you have to pick which one to go with while locking out the other one for that playthrough.
The only difference is this quest doesn't say return x to person a for one reward or person b for a different reward. You just have to make a choice and that's the choice you're stuck with for that playthrough.