The dual channel Hive receiver is designed for systems with central heating and where hot water is preheated and stored in a hot water cylinder.
The single channel Hive receiver is for combi boilers where hot water is generated instantly, so no time control is required for hot water.
The wiring to the backplate is different, and the two versions of the Hive are not interchangeable.
It is possible to wire up a dual channel receiver to work with some combi boilers, and simply ignore the hot water settings. But this is not very professional. The problem comes in that some Combi boilers have 24v for their control and will be damaged if connected to the dual channel version of the Hive putting applying 230V to the 24v circuits.