Due the size of a room and the width of the carpet roll, carpet installers sometimes have to cut or "sidematch " two pieces of carpet next to each other to fill the space appropriately.
Sidematch is defined as the appearance of a shade or hue variation between joined carpet panels. It is important to note that this is not noticed usually until both pieces are next to each other. This is because, when carpet is being manufactured, the dye used to color the carpet may vary between mixtures, causing different "dye-lots".
In order to avoid issues where it may appear the color does not match the installer should lay both pieces of carpet down in the same direction for both cuts. If the pile of the carpet is running in different directions, that can also make it appear to be different colors on each side of the seam.
Sometimes the appearance of different colors is due to shadows from windows and is not actually a color difference at all. If you come across this issue, please feel free to contact Customer Support!