You have to be careful with terminology, and also take the environment into account, as it is very easy to misunderstand how things work, and misinform others who read it.
When you start with a tuner, a tuner can receive a single transponder at the time. That is true for all tuners, S, C and T.
From this it follows that if you have a module with two tuners (in marketing called dual tuners or twin tuners), you can receive two different transponders at any given time. So contrary to your statement, such is module IS identical to two single tuners.
However, if you have TWO S tuners connected to ONE cable, both tuners will be restricted to what can be transported over that single cable, which in a DiseqC setup is a single LNB quadrant, theoretically 1/4th of the available transponders. If you have a Unicable setup, you can receive two transponders, even if you have only a single cable.
If you have an FBC C module, you have 8 tuners connected to one cable, and the possibility to simultaneously receive 8 transponders. I haven't seen an FBC T module yet.
For S, it is a bit different. An FBC S module has 2 root tuners, connected to each of the inputs, and 6 leaf tuners, which are dynamically looped through on one of the root tuner inputs.
If you have a DiseqC setup, both root tuners will behave identical to a dual/twin tuner module. The 6 leaf tuners will be able to tune transponders in either of the quadrants locked by one of the root tuners, identically to having a dual/twin tuner with a single cable. If you have a Unicable setup, all 8 tuners can tune to a different transponder over a single cable (providing your setup can provide 8 SCRs).
For both twin/dual tuner S modules and FBC S modules you can mix both setups, so you can have a DiseqC setup on one tuner, and a Unicable setup on the other one. Like you can with two single tuner modules.
Currently in use: VU+ Duo 4K (2xFBC S2), VU+ Solo 4K (1xFBC S2), uClan Usytm 4K Ultimate (S2+T2), Octagon SF8008 (S2+T2), Zgemma H9.2H (S2+T2)
Due to my bad health, I will not be very active at times and may be slow to respond. I will not read the forum or PM on a regular basis.
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