Yes they will take the payment even though you already made a payment this month ... however have you gotten any reply on the installment agreement request you made ? Next time, instead of completing the 9465 thru the TT system, do it directly at the IRS web site ... there you will get an instant acceptance or rejection.
Payment plans take weeks to approve so the payment will not happen until
then ... they will send you a letter when they decide but for now you can
expect the payment to happen anytime now ... OR you can make
payments directly on the IRS web site now ...https://www.irs.gov/payments
You can check on the plan or adjust the plan here : https://www.irs.gov/payments/online-payment-agreement-application#ibtn
