Carlton is in the AXOR range of products. This is Hansgrohe's Lexus brand. The ThermoBalance line of valves is the Toyota version Hansgrohe line. Both are dependable, but AXOR has more performance and style.
ThermoBalance III is capable of running 3 items, controlling flow on port 1&2, but not on port 3. Piperca said he only wanted to run 2 items in his shower so I will explain how he can do it with ThermoBalance.
ThermoBalance II can run two items, but you cannot run them both at the same time. The valve lets you set the desired temperature and control volume to each outlet by turning the handle either clockwise or counter clockwise from the off position. All of this is controlled on one knob and lever combo handle. Basically two handles on one valve stem. Sounds impossible, but it works great.
Thermobalance III can be used for two features but you have an extra outlet. The unused outlet should not be capped or plugged or it can damage the ceramic valving. So the way to pipe it is to run the bottom outlet 1 up and tee into outlet 2 riser that feeds the shower head. Outlet 3 pipes to the hand shower. This setup allows the shower head or the handshower run together or seperate. There will be an ability to control volume to the shower head and to bias the handle in the shared position giving either the hand shower or the shower head more pressure and the other less pressure. But the handshower must be full on when it is running solo.
You could share both and get volume control on either if you piped outlet 1 and tee into outlet 3 riser, but you will get cross flow through the valve until it is trimmed out. This is okay for new construction, but crossflow on a remodel can be a hazard.