There are some species that people seem to be able to keep in pairs, i've seen some jacksonii, melleri and hoehnelii that was successfully paired together.
However, this is usually very experienced chameleon keepers that know what they are doing.
I strongly suggest that you keep the different species individually, maybe for years, so that you have a behavioural referense to fall back on. Without that you have no way of knowing what behaviour is due to the co-habitation and what is not.