how to distinguish an original Vu+Ultimo from an clone one!?

It should also be mentioned that the above guide is more specifically aimed at the German market, Satco officially distribute to much of Western Europe but they are NOT the UK distributor, the UK and Southern Ireland (at least as it stands) are considered a region in its own right as regards distributors so what follows on that guide won't necessarily be the same for the UK and Southern Ireland and likewise any warranty as far as the end customer/buyer is concerned will ultimately be with the place they purchase.

Quote from warhead1999

to be honest i have solo original & a duo clone

Although it mentions clone with regards to the PDF guide above is not what we would generally describe as a clone/counterfeit - They're both the genuine thing the PDF is talking about it's just in relation to spotting a grey import that was never intended for the western Europe market, so it's still genuine but could perhaps be an issue if you ever need repair under warranty. The guides in respect of the VU+ Ultimo only though in any case, no other VU+ models.

Couldn't agree with regards to the clones and the value, you have zero guarantee with them and it's quite clear there have been a number of issue with them and faults developing after a short time in the field, but that's really not what this thread is actually about in any case. :)