You are able to define more than one type of virtual reward (e.g. different types of currency, lives, booster packs) to give to users.
To add another currency, go to My Apps > Manage Monetization > Define Rewards. Please note, you will need to update the Currency Redemption method in your app as well when you add additional currencies.
You can select a different currency to reward users at the placement level. Go to My Apps > Manage Monetization > Define Placements and click on the name of the Placement, in this example it is “Level Failed”. If you use the Default Reward, the virtual good that is given to users for that particular placement will update dynamically in the future should you change the Default Reward.