It is normal for fabrics to exhibit different shades of the same color between different dye lots of otherwise identical material. These differences are caused by changes in temperature, dyeing time, and other factors during the fabric's dying process. It is expected garments manufactured at different times can/will show variations in color shade.
We even witnessed variations in color between the same costume first-hand while inspecting screen-used outfits during our research trips to the studios. It is not a defect in any way and is viewed as “normal” and within factory standards.