I did the following: created a dummy satellite 28.3, because it is not allowed to have two 28.2 in Duo.
I also entered that satellite into satellites.xml.
But without any transponders entered in advance.
(I want both tuners to have separate 28.2 satellites)

Then I scanned all the transponders manually one-by-one.

Vu+ Duo with PLi makes a mess. Some channels are recognized as data streams,
and not only they are not allowed to be selected to watch, but also somehow moved to wrong transponders, some transponders deleted, etc.

For example: scanning 11604V gives 7 data streams, I suspect, because this transponder actually has one data stream together with regular channels.

Also the BBCi streams on 12441V are recognized as data streams.

But what is interesting: both 11604V and 12441V do not remain together, the last manually entered and scanned remains, the other transponder disappears.

Even if I convert BBCi channels to TV with DreamSet, when afterwards I scan 11604V, BBCi channels are moved into 11604V and the 12441V transponder is deleted. Which is crazy.
Perhaps an additional problem is that those streams are named the same, I will try renaming them differently.
There are more channels wrongly identified as data, and more transponders deleted,
I am missing 9 or 10 transponders of 60 that are reaching my location.
I scanned successfully 60, now I have 50 or so, about 10 were deleted by Duo (probably when scanning some other transponders) without informing me about it.

So, it seems that it is better not to scan with Vu+ because the results are unpredictable.
Better to find good ready-made settings or try making them with an editor.