Just change the remote control address for one of them. Look in the manual for the steps.
Here you go:
With the receiver on, press the Info or System Info button on the front panel,
Press and hold the SAT button (about six seconds) until all mode button backlights come on, then release.
Use the number buttons to enter a number from 1 to 15. The light will blink off after each digit is entered and then return to a steady light.
Press the POUND (#) button. If the code entered is valid for the remote, the SAT mode light flashes three times.
Press the Record button. The number in the Remote Address field should match the one you input.
To verify the code, press and hold the SAT mode button until the mode lights come on. Then press the POUND (#) button twice. The light will flash the address.