Hi,
I have suet balls, not with the seeds, plain suet....and lots of Woodpeckers. I have them in the back and front of the house and it isn't at all unusual to have woodpeckers at both stations.
I do have more than one pair of Hairy's. One male is very easy going and doesn't frighten off when i open the door, but continues eating...8 feet from the door...yesterday at one feeding, he ate for 12 minutes..one stretch. His wife flew down and took a position two feet from him on a log feeder ( a 1 ft. log Paul drilled full of holes and I filled with fat and peanut butter) . The Mr. didn't flinch.
The other male is very timid....stays short time only... so yes, I ahve more than one pair.