The data sheet is not clear and I've never seen that before, except some woofers have dual voice coils... Can you see any small wires soldered to the terminals?
I would guess that two termminals are connected together and connected to +, and the other two terminals are connected together and to - .
Do you have a multimeter to check if any of the terminals are connected together?
If you have a series resistor (a couple-hundred ohms or so) to limit the current, you can simply try it out. If you connect a "short" with a current limiting resistor in-place, nothing bad will happen.
...is it not just Gnd and V+ usually?
If it's just a speaker/transducer and not a "buzzer" or "beeper", you don't connect V+. You connect signal and ground. It won't make any noise with V+ connected. V+ won't hurt a piezo, but it's not good to put constant DC voltage into a speaker with a coil. 5VDC into an 8-Ohm speaker coil is 3 Watts of heat, with no sound. 