The Thameslink units have no duplicate indicators so far as I know. Perhaps because these trains were intended to use ETCS in daily service right from the start, the situation is a bit different to something like the IET which were delivered with ETCS, to remain out of use indefinitely.
Strictly speaking, there is to my knowledge no commercially available STM for TPWS. An STM is a unit which communicates with an ETCS computer via a digital PROFIBUS interface according to the protocol defined in UNISIG
Subset-035, thus minimising the amount of work needed to integrate additional national safety systems.
The TPWSfour however has simple interface consisting of various input/output pins which are turned on and off to indicate the device state, so anyone wanting to integrate it with an ETCS control unit would have to build their own hardware to interface to it and write their own STM, or integrate it via some other route.