Press Button A to complete NO circuit on channel 1 Press Button A again and NO circuit on channel 1 returns to open Press Button B to complete NO circuit on channel 2 Press Button B again and NO circuit on channel 2 returns to open
It will need to config both channels as hold / toggle, then program button A to channel 1, button B to channel 2.
But from your description,
If Button A is pressed once and then Button B is pressed once, Channel 1 NO circuit will close, as soon as Button B is pressed, Channel 1 NO returns to open and Channel 2 NO circuit closes
If Button B is pressed once and then Button A is pressed once, Channel 2 NO circuit will close, as soon as Button A is pressed, Channel 2 NO returns to open and Channel 1 NO circuit closes
Our relay will be configured to something like interlock-latching.
So I’m afraid our receiver can’t be configured like this way, you might need some more advanced logic receiver or something with software customization capability.