I've used a $75 voucher on one of my personal websites, and am wanting to use another one for another personal site. I've tried this already and it yielded no clicks... I'm assuming you can't use more than one voucher even if it's for a different site? (I used a different google account)
You just can not use more than one voucher in an account. But no matter if you use them in different accounts. Check your keywords and your campaign. sometime with negative keywords, you will not get any click
Some seller are selling $250 voucher, they claim can be used on old account, I haven't tried myself yet, but it may work for you.I am not 100% sure, just a suggestion.
What is not possible? Have you understood what he is asking? It is perfectly possible in his case as he is using it in 2 different google accounts. Read before you post. Posting just to increase post counts is not going to help any including you. @McCoyH - Check if you have added your billing address. Check if your bids are too low (Try auto bidding). Looks like something is not ok. If voucher is not usable, it will give a error when you try to apply it.
I don't know if you can use multiple vouchers at the same time. I'll use them one after the other if I were you. I have a $100 voucher waiting in my account. My forum is new so I want to add more content before I start paid advertising