overcount
verb
over·count ˌō-vər-ˈkau̇nt 
overcounted; overcounting
transitive verb
: to count more of (people or things) than is accurate
overcounted the votes
overcounted the number of students enrolled
overcount
ˈō-vər-ˌkau̇nt
noun plural overcounts
an overcount in the census
Word History
First Known Use
circa 1594, in the meaning defined above