I believe it is Model #: 06056M
I'm not terribly familiar with that display, but I don't think there is a way to tell it to ignore a sensor on one of the channels.
Since the signal is weak, you might try setting one of your sensors to channel A and see if it locks on to yours instead due to the stronger signal.
You might ask this question on Acurite's support board, support.acurite.com, for a response from someone who has worked with that display and a response from one of the official support techs.