I was in a situation like this with a student loan. My loan went to a collection agency, but was not sold to it. The school said to make the payments to the CA - which in turn doubled the amount due.
I thought I was being ripped off. So, I mailed my payments to the usual payment address. Mind you, I did not know if the collection was on my CR. I didn't know about this stuff until much later.
Approx. 1 year, I checked my CR and the collection was listed. I called the CA and told them this was paid to the OC and they told me to dispute with the CB'S and they would not verify.
I did and the collection was deleted, along with the OC account.
I made payments by the way.