Dual voice coil. how many ohm is each coil?? They make them to add flexibility for how you wire them up. You should always use both coils, that is why you need to find out the ohm rating for each coil. depending on how you wire the coils, series or parallel, you could overload your amp if it is not stable down to the ohm load. look at your amp, is it stable down to 1/2, 1, or 2 ohm? Dual four ohm coils run in parallel will make a 2 ohm load, in series will make an 8 ohm load. If your amp is not stable down to 2 ohm and you run a 2 ohm load to it, it will burn up.
1982 Cutlass Supreme - mild SBC, tons of fun! The summer toy
1996 Silverado Z71 - the hauler
2002 Bonneville SLE - His / project
2003 Bonneville SSEi - Hers / never ending project black mirror