Ok, I wanted to make some color variations in clothes, so I changed one of the textures, making a green shirt into a blue one.
I loaded the mesh into the CS, set the biped objects etc. So if I equip the shirt to an npc it shows up correctly in the CS, but ingame nothin has changed.
Even when I remove the clothes of that npc in CS, he still wears his stuff when I look at him ingame.

I wonder if I am doing something wrong? when it all shows up correctly in the CS.. hm