Yes! You can order multiple wristband colors of a single design.
On a desktop, use the "Add a Color" button in the bottom left and choose your additional color in the pop up window that follows. You can see the button highlighted here:
On a mobile device, select the "Product" option, followed by the "Add Another Color" button in the following pop up window. You can see these steps highlighted here:
On both mobile and desktop, you will see a group of color swatches. Simply click on the new color you'd like to add to your order and hit the "Add New Color" button.
You've done it! A new color version of your design has been added to your order.