I am managing two separate Google AdWords accounts and with one I was able to add 3 different promotional codes so I got $300 of Google AdWords for free.

I signed up for Google AdWords for another business with a separate login e-mail address. I used the code that I was able to generate and a few days later I recieved an additional code in the mail. I tried to use this code and it said I was only able to use one promotional code per account.

Does anyone know why Google has this inconsistency? Was I just lucky the first time or is it possible to use multiple vouchers?

Thanks