"mbjunki.." knows not much. A splitter makes one output to two monitors and the screens are identical images.
A computer with a video card that has more than one output (VGA, DVI, HDMI, Display Port, S-video, RCA composite type ports) can run two or more monitors, depending on the card.
Using many video systems in desktops and laptops for over a decade with multiple monitors. Using computers since 1962.