...mmmhhh I think you will get problems when changing the polarisation vertikal/horizontal or the band low/high. Witch tuner would that do? Both tuners? Is there a master and a slave....
Maybe unicable will work fine but I prefer discret connections using a "sat-verteiler" like this.

That´s what I mean. Loop (internal or external) with normal lnb produce problems. So your problem ist that it doesn´t work.
Sometimes menue-options maybe crazy.
Before you install a 3rd cabel betwenn tuner and dish think about unicabel, because anyway you have to chance the lnb.

@Burkhardtsdorfer
This is not correct; the Loop through modes, internal on twin Tuners and external if you use a splitter (not a priority switch), are working as expected:

The first tuner that is connected with others, and gets to be active, defines the polarisation and band used with the common SAT connection.
The other tuners using the same Connection will only be used with channels on the same polarisation and band and only these channels are available, the remaining are grayed out in the channel list, if no further Independent tuners are available.

In my Special case, I have only two Independent SAT Connections, used by 5 Tuners (DM7080) - two Twin tuners and one single tuner. The single tuner is connected "external" with one Twin tuner using a splitter and the Twin tuner itself is connected "internal".
The second Twin tuner is connected to the second indepent SAT Connection, also using internally Loop through.

So, I have 3 Tuners using the same Connection and 2 Tuners using the same second connection... The most german channels are available with horizontal Polarisation and low and high band, vertical Polarisation is used by very few, not really important channels.... I have no Problems with this Setup and a Maximum degree of freedom in using my available SAT Connections with recordings, Streaming, etc...