The colors produced by the anodizing process are subtractive not additive as in paint systems. The anodized film transmits light to the substrate and is reflected back through the film. In short, it acts as a filter rather than a reflector as in a paint system.
In addition to the dye, anodized color appearance is influenced by alloy, surface finish (specularity), anodizing bath temperature, time, and constituents. Thus, getting colors to match from order to order is extremely difficult. We recommend establishing a color range that is acceptable and processing orders together as much as possible to minimize variation.