At the moment, the dye system has primary dyes and secondary dyes and double modules that have a primary and a secondary color. There are 11 colors and 5 shades:
Light / Pale
Medium
[None]
Deep
Dark
Black
Blue
Brown
Gray
Green
Orange
Pink
Red
Purple
Yellow
White
That's 55 combinations for the primary and secondary modules, and 55x55 possible combinations for the double modules giving us a possible 3,135 possible modules, which as you might suspect, not all are in the game.
The armors have one dye slot, so you either equip a primary dye module, a secondary dye module or a double dye module, and with not all the possible combinations in the game, you are limited to what you can do.
What I suggest is to remove the double dye modules from the game and make all 55 possible colors and shades available either from the Cartel Market, crafting or from NPC drops as we have them now.
Also change the dye module slot on the armors to have two dye slots instead of one. Make one a primary slot and the other a secondary slot.
This would give those dying their armors 3,025 possible combinations with the colors, 55 for the primary slot and 55 for the secondary slot. It would allow players to change either the primary color or the secondary color without needing to change the other slot.
How difficult would this be to implement? It would require a slight graphical change in the armor modification window for each armor, adding a second dye slot, and make it possible to place a dye module in there which then changes the secondary colors on that armor. The current dye slot would have to change only the primary color. I don't think it would affect previewing, but who knows if changing the way the slots work would affect previewing. NPC drops, Cartel Market and crafting would need dye modules and schematics added.
Please change the dye system.