A:Answer In this case you can only SPLIT/duplicate the signal and you will need to buy a "HDMI SPLITTER" and they are quite expensive for what you get.
If you want to "EXTEND" your display:
Your PC may have a VGA port on it, I suggest you plug the 3rd monitor in there and see if your PC detects it. If not, you may have to boot to BIOS (power on PC, and immediately tap repeatedly F1, or F2, or DELETE , depending on your BIOS requirements (I do all 3 in repeated sequence until I get into BIOS) when in BIOS, you will have to cursor around until you find display and see if there is an option to activate onboard graphic card)
If VGA is not available, or your PC only allows onboard display *OR* additional card display, then sorry, you will need to buy another video card for your PC... They are not too expensive unless you are a heavy gamer and want massive graphic processing power and memory.
There is a DUAL DVI card out there if you cannot find a dual HDMI card.
Even better is DISPLAYPORT and the latest version allows daisy-chaining of monitors off one port, I don't recall how many, but I think 4 monitors off of one display port. You will of course need a monitor with displayport and there is not a huge selection yet. In my case, surprisingly, the cost was nominal to have VGA + displayport.. I got it here at BestBuy for an insanely great price! 27" $190 Dell E2715HM 2734 IPS LED HD , it is 1080P, we love it.