If you were wondering why they're called Acorn Woodpeckers, this should provide a bit of clarity. And yes, that is the head of a second woodpecker right behind it. Teamwork.
"Acorn Woodpeckers are very unusual woodpeckers that live in large groups, hoard acorns, and breed cooperatively. Group members gather acorns by the hundreds and wedge them into holes they’ve made in a tree trunk or telephone pole."