So here's what happened:
I got a $25 Google Play card. I tried to redeem it on my account, but I got an error due to my country. I used VPN. It still didn't work. Trying to solve the problem, I went into my secondary account, and I wanted to see if it would work, but I would cancel it before it got redeemed. But, it turns out I redeemed it on my secondary account.
So how can I transfer the credits? Can I?