MySQL Query duplicates sum for left join

I have 2 tables, Greeter_Detail and ZipCode_Details I'm trying to SUM the total of People and Families from and Greeter_Detail and join them on ZipCodes, but I get duplicates. ZipCode_Details has city and county info. Can anyone help, I've been on this for hours. Seems like it should be straight forward. TIA! SELECT SUM(Families), SUM(People), Zipcode, ZipCode_Detail.Zipcode_D, ZipCode_Detail.City, ZipCode_Detail.County FROM Greeter_Detail LEFT JOIN ZipCode_Detail ON Greeter_Detail.Zipcode = ZipCode_Detail.Zipcode_D WHERE $dateRange GROUP BY Zipcode