The guy who now buys the heads outside the gates in Cordor is only paying for the first head in a stack presently. Not sure what's changed or when. But if you have a stack of 10 heads he will only pay for the first one, but take the whole stack.
I just experienced this, a moment ago. Another player reported it to me day before yesterday. Can others confirm this please?
Suggested Work Around: I'm out of heads to try this, but I bet if you separate your heads into stacks of 1, you will get paid for all of them.