[CQ-Contest] SO2R Hardware Question

[John Geiger]

I have 2 radios that I would like to be able to use in dual receive mode,
meaning I can listen to both at the same time.  They would be using 1
antenna, and only one radio would be used for transmitting.  I would like
to be able to use both on the same band for split frequency DX pileups.

What sort of SO2R interface do I need to accomplish this?

73 John AF5CC