DVI/HDMI + S-Video at the same time on the same TV??!?!?!

Hi, yesterday I finally got a nice Sharp LCD with HDD integrated.
I quickly connected my Nvidia GT7950 via DVI/HDMI so to record on the
LCD internal HDD the streaming video coming from a japanese online tv.
The fact is...HDD cannot record any signal coming from a digital input
(I think for copyright reasons) and let me record only S-VIideo and
any analog (like scart...) and here it comes my problem:

I've connected both the DVI/HDMI and the S-Video OUT to the Sharp LCD.
The rational was to be able to watch the pc via DVI/HDMI while
recording the S-Video signal. But the nvidia control panel / Set Up
multiple display shows only the single display option (Sharp via DVI/
HDMI).

Any idea why is that? Why I cannot select multiple screen as when I
was connectiong both the EIZO monitor and an old CRT screen?

Any solution or suggestion on how to solve such a problem?

Tks,

Ataru