BSkyB and Freesat are from Astra2/Eurobird 1 at 28E. They essentially use exactly the same Channels and it is only the EPG that is different. Although clearly by definition Freesat cannot decode Encrypted Channels
You cannot get both Astra 1 at 19.2E and Astra2/Eurobird1 at 28E on your TNT dish ............ you have fallen into the trap of assuimngn the Receiver is intelligent.
A "Satellite" as stored by a Receiver is merely a list of labels, tags and tables of parameters.
As frequencies and other parameters are re-used across the arc (Something which is possible only
because you cannot receive Channels from more than one Satellite at once with a single fixed dish/LN
, when you scan a "Satellite" called eg Astra 2 but with a dish aligned to Astra 1 at 19.2E, you will (and can) only get Astra 1 Channels ..... but not all of them - just those that have parameters corresponding to the pre-stored list.
Edit: TNT is at 19.2E, along with loads of FTA German Channels ..................... so that is where your dish is aligned to. Which is why when you scan the "Satellite" labelled Astra 2 you still only get German Channels.
Imagine altering the name of the "Satellite" to "The Real Satellite My Dish Is Pointing At, But With Only A Partially Corresponding Data Table" and all will be clear.
If still not sure, look at the up to date listings on eg Flysat, Lyngsat, KingofSat etc.