Serial number type: You can create the multiple coupon codes with random serial numbers.
Daily type: You can create a coupon code with one serial numbers. 

It’s an unique value to validate the coupon.
It’s 4 characters and you can customize the prefix as per use.

Go to Coupon > Dashboard, and click 'Add a coupon' button to add a coupon campaign and then go to Dashboard find the campaign you just added. 
Click 'Issue Coupon > Issue Coupon - Actual' and a pop-up shows up, enter the coupon name and quantity and Click the 'Batch Issue'
You’ll see the name of coupon at the dashboard and can download an excel file that contains issued serial numbers.

Using Campaignkey value, you can give general items that’s not reward items.
For instance, for a coupon A, you can use servicecode and campaignkey to determine a coupon A and give a selected item.
Please check Reward Server Integration Document for more information.

It’s showing how many coupons are actually used in %.
You can check Collect Rate at a coupon report.

If you integrate Coupon API, you can use a basic UI form from the integration guide.

You can go to Coupon > Dashboard to cancel any coupon.
Click a ‘Stop’ button when you click a ‘Use’ button to cancel. 

In case of serial number type, only one code can be used for a user and one device.
To use two codes, a separate campaign has to be created to be used separately.
To create duplicatable coupon, use daily coupon type and limit the usage for user.