To combine them, put all of one like color into your main pack (CC). Double click one and when it asks you what you would like to dye, target another dye of the same color. The original dye that you targeted will now have two charges. The dyes that dropped in this ToT event can be combined up to 50 charges per "bottle".
EDITED: to clarify that all dyes must be in your "main pack" (and not in sub containers) in order to be combined.