+ to + - to - on a dual 4 ohm = 2 ohm load. most 2 channel amps are stable at 2ohms stereo. but some or most are not bridged usualy 4 ohm stable bridged. + to - + out to amp - out to amp = 8 ohm load which you can run to an 4 ohm stable amp.

You can connect speakers up any way around ,if its one speaker with 4 connections then these extra 2 terminals are often for a continue through to the next speaker along the line ,.just use a small 9v battery and then connect to two terminals to find a bleep as you touch two of the terminals then you know where to put your wires