Swift Technology is just a switch nothing more it changes it from 2 ohm to 8 ohm. Put it on 2 ohm run one wire to the box terminal on the 2nd subwoofer do the same thing run it from the subwoofer to the box terminal inside the box itself so you have both wires inside vs using two box terminals on the box and two wires going to the amplifier. By doing it with one box terminal and the two wires from the subwoofer going to said one terminal you then only have to run ONE Speaker wire from the outside of the box terminal to the amplifier giving you a 1 ohm load as well. THAT is what I am trying to get through to you. Yes you can use both terminals on the amplifier but you can ALSO set it up to use JUST ONE! Yes you can do it the other way as well. It WORKS the same either way. Why waste the extra wire if you don't need to just adds to the cost overall and the amount of wire running. But if that is how you want to do it then w/e as Dragon said it will work.
That means less cutting into the box and less cost for another box terminal and wiring. Was trying to save you some money since either way works but one is less expensive and less wiring inside your trunk showing. It isn't rocket science,lol.
edit: btw my intent wasn't to come off as rude so if I did my apologies. Recovering from another surgery that has been painful so between that and the meds been a little short with people the past few days.