Okular does not open document in tabs from command line

[Angelo Graziosi]

I have Okular configured to poen PDFs in tabs but when I use it from 
command line, e.g.

okular foo.pdf
okular bar.pdf
foo.pdf and bar.pdf are opened in windows instead of tabs. There are two 
instance of Okular instead of one with two tabs.

Only in GUI the PDFs are loaded in tabs... :-(

Maybe there is a trick I do not know o maybe this is a feature to add in 
Okular.

TIA,
  Angelo.