I just tested that with Keepa on this phone [1] [2] [3] [4]. The charts are different for all 4 colours but personally I like it that way. Usually I have a preference for colours. However, sometimes I don't, and if I'd buy for someone else who knows? Its gonna depend. I checked the settings and was able to compare different Amazon versions (per country) but not merge colours of the same item.
With The Camelizer it shows the wrong price (I take it it grabs Amazon US price but I'm not sure).
I don't have an account on Keepa or CamelCamelCamel. Perhaps having an account gives further benefits.