Nope,only 1 human and zombie class can be available for each clan.
If we type '/clanclass', a list of clan names will appear. Example -
Then if the clan member, such as [AC]Capt. selects [AC]Assault Clan, he will get this -
[AC]Human - Deagle,Shotgun,MP5,Cures,Heals.
[AC]Zombie - Explodes when dies, More damage with Chainsaw.
But if a clan member of UC selects [AC]Assault Clan, this message should appear -
→→ You are not a member of Assault Clan!