DEAD DROPS

If you've been doing quests for both rogues, you'll have to choose for whom you want to complete the fourth quest, as it involves killing that rogue's rival. It's not a choice made in-game, but rather depends on whose quest gets turned in first. Should you turn in both quests at the same time, it will default to Harsh Decisions as mentioned above.

If you wish to leave your decision of which rogue to side with to the absolute last moment while still maximizing your gold, it is best to complete the Denerim drop last and leave Cam of Redside alive while False Witness is active. Then, if you wish to side with "K," turn in Dead Drops, accept New Ground, then kill Cam and turn in False Witness before moving against "D." Technically you can place all four barrels, but this prevents you from turning in other Favors to the bartender, such as Correspondence Interruptus, if you have not decided on a rogue to side with. New Ground will become the final quest.

If you wish to side with "D" while maximizing your rewards, simply finish and turn in both quests at the same time. Even though the game only shows the reward for one quest, as is the case with any other collection of quests in which multiple can be turned in simultaneously to a single NPC, the inventory shows that sovereigns have been added for all completed quests. Harsh Decisions will become the final quest.