MultiCurrencies

[xuroth]

Use a conditional branch for the event that has 'Battle Processing' in it. If the player wins, use a 'Script' command to manually give the player the alternate currency.

For the dual currency battle set triggers in battle:
Set up both enemies to drop 0 gold, gil, whatever currency you use.
When you set up the enemy group in the database, edit the battle triggers (event commands)
when enemy 1's hp = 0, Script command to give 20Gil
when enemy 2's hp = 0 Script command to give 2 Gold
when both enemy 1 and 2 hp = 0, Then display a message 'You gain 20Gil and 2Gold!'
(of course this means it won't show up in Window_BattleResult, but it lets you have the desired effect without needlessly re-writing the end phase of the DBS or this script)
If this isn't quite clear enough, I can give a more thorough explanation, but essentially this is what you are doing.