There seem to be some problems here that don't make sense. In the base set, there is a card called
Hireling that is in the Treasure deck. In the expansion,
Munchkin 4: The Need for Steed, there are some Race- and Class-based Hirelings that are in the Door deck. There are also some other types of Hirelings in other sets (
Munchkin 5 and
Munchkin 8). The Race- and Class-based Hirelings have names like
Dwarf Hireling and
Wizard Hireling.
All Hirelings are treated like Hirelings, not Classes or Races, as they are a special type of card. They use the
rules from Munchkin 4 when you have multiples of them. Perhaps looking over those rules will help sort things out.