I have the exact opposite experience.

I returned two products, got two different return codes, was supposed to send each back separately.

During the return (it was a Kohl's return), I forgot about the two different codes and gave both items to the clerk, who then packaged both items with only one code.

I got credited for the first item a few hours later. At that point, I realized my mistake of packaging both in the same return, but thought it was a lost case and chalked it up as a loss.

Imagine my surprise when, a few weeks (!) later , I got credited for the second return as well. How did they figure that one out? I don't know.

The most amazing customer service, where I did not even have to mention it and the error was still rectified.