Well, if you use Durabrite pigment ink, it is likely something called "color shifting". Color shifting is when the *heat* from the press changes the inks in the designs to different colors.
Durabrite is not the only ink that can suffer from color shifting, but it is the one to do it the most.
To fix color shifting, you can try to reduce the amount of yellow printing by changing that setting in printer preferences. For my c88+, I use +5 magenta, +5 cyan, and -10 to -20 yellow. I do not have color shifting with my Durabrite ink.
There are others who have tried those settings with their Epson printers and still had color shifting, so sometimes, it does not work.
Usually an ink change is the sure fire way to eliminate the problem. People will buy a 3rd party ink from an ink supplier that carries either refill carts or bulk ink systems for their printer model.
Some of these suppliers are inkjetcarts.us, shopdyesub.com and inkjetfly.com. There are others, but I hear these names frequently.