The two signatures is a good policy, but not one the bank will take responsibility for enforcing. Still, you don't publicize that part and it's part of what's checked in the audit, so it makes a good practice.
With our middle school PTO, the bank our group wanted to use refused to allow us to have two signatures on checks. I never had that happen before, but they were very firm.

For some reason, the group really wanted to use THAT bank so we changed our policy to where 2 people signed the reimbursement form (internal), then the treasurer prepared the check BUT he did not have signature authority. He had to take it to another officer (Pres, VP) for a siganature.

So it was the same safeguard - it took 2 people to prepare a check, but not two signatures on it. One had physical custody of the checkbook, the second had authority to sign.

I believe 2 signatures is a requirement for our bonding insurance, but I know for sure it is not a requirement for 501c3. It's just really good policy, no matter who is checking up on you.

The two signatures are PTO rules not the banks. They only need one authorized signature on a check to cash it. I don't believe it is a requirement for 501c3 but I could be wrong. And we most certainly don't pay an extra fee for 2 signatures - I would be looking around if yours does!

Any PTO board member can approve a check request. Our PTO has a Treasurer and two Vice Treasurers, and any one of the three of us sign checks.

Although the 2 signatures are great for internal control, is it a requirement for 501C3 purposes? Thanks!

If your bank is charging you for two signatures, go find another bank. We order our checks with a second signature line, no extra charge. Depending on your bank, they will or they will not actually visually verify that there are 2 signatures on each check. Our bank told us it didnt' verify. That's fine with us - we just don't tell our members that it's ok to write a check with only one authorized signature so everyone understands there's sometimes a delay getting that second signature. For us, two signatures is an internal control, and one we will not consciously violate even tho the bank doesn't care. Maybe your bank visually inspects for 2 signatures and that's why they have a fee for it. Ask them if you can just skip their visual inspection but still have 2 signatures for your own control procedures. If they say no, shop around for another bank. There are others who will give you a small biz checking with no fees.