From the announcement:
Get Both Zombie Hordes Bundled together for one Special Price.
You get 200 Zombie figures that can be used to represent Zombie Soldiers, Doctors, Medical Staff, Patients, Firefighters, Paramedics, Police, SWAT, and Civilains on your game table.
Save $100 compared to buying the two hordes separately.
If you have been looking for a way to fill your table with Basic Zombie Extras, here is your chance.