Data for Cape Hansen (HANS site_id)

I noticed that for the site_id HANS, the observed number of nests both for adelie and chinstrap is 13381, with data collected on the same day 17/12/2003 on the ground. Maybe they do have exactly the same count, but could it be a mistake? Adelie has also been counted the following year 17/12/2004 with again the same count (13381).