Comcast 2nd Cable card fee?

My first Cable card device is free with Comcast Xfinity. Does anyone know what charges they would add to my account if I add another Prime with another Cable card?

It may vary per your location, if they even offer a 2nd one.
In some areas, they no longer offer them
I think they are $10 at least for me, and just before I dumped them couple years ago, a note on my bill said it was going up to $15 a month.
They used to be only $5, that became $2 after "customer owned equipment discount" they legaly had to apply, but times have changed.

They're charging me $9.95 for "Additional outlet, includes CableCARD". They're also crediting me a $5 "Equipment discount" for having my own cable modem, so that section of the bill totals $4.95/mo. Your local pricing may be different though.

Below is mine from xfinity .. plus they give me a credit for owned equipment. I think it might depend on your package. They recently stopped charging me $1.99 for each.

Qty 2 @ $0.00 each