Why do Carthage have so many spearmen/repetative units that do exactly the same jobs?

Spears/pikes:
elite african pikemen
sacred band
libyan spearmen
heavy libyan spearmen
libyan-phoenician spearmen
heavy libyan-phoenician spearmen
others

Infantry (swords):
Light iberian infantry
Heavy iberian infantry
Assault iberian infantry
elite african infantry
others