Can you pay twice with Direct Pay? (IRS site)

[gumbootkitten]

I made a payment (selected "Extension" as my reason) using the IRS Direct Pay site. It's still processing from yesterday. Now I am wondering if I should pay a little more just in case my estimate was wrong. But I don't know if the system will get confused by a second payment?  Is it okay to make two payments for same reason (extension)?

[KristinaK]

You can choose another reason - Payment with return. Just make sure that the year you are paying for is selected correctly.