Calculating the resistance needed
You dont need any resistor if you just wanna drive those motors with 12V supply. 0.32A is the current that your motor draws at steady state for 12V input. You just have to connect both motors in parallel to the 12V supply. They will draw 0.32 + 0.32 = 0.64A in total from the supply, while your supply is able to source up to 2A. However the motors will draw high peak current initially while starting. Later on back-emf is generated, which reduces the peak current to the steady value of 0.32A.