Paying IRS using credit card when married filing jointly. Can I make 8 credit card payments?

Hello. I am paying the IRS using credit card for married filing jointly. Can I make 8 payments? I know I get two per processor, to make four payments, but since we are filing jointly, can I make 2 per processor per person? If so how, as it always asks for primary taxpayer, and I cannot change that obviously as on the return it lists me and my spouse is secondary. Will it just take 4 payments if I have a secondary taxpayer on it?

I want to pay my tax bill, and get double miles on my CC. Unfortunately, the new card I just got has the lowest credit line I've ever gotten. I called and they will not increase it or move credit from any of my other credit cards to increase my credit line.