That is the strangest way to wire two subs together I've ever seen.
From those pictures we can't even tell if they are wired in series or parallel, I'm guessing parallel, but that is nothing more than a guess since I can't see which terminal is positive and which is negative.
The resistance depends both on the subwoofer and how they are wired. You need to tell us how many voice coil each subwoofer has, what resistance each coil has, and how the coils are all wired together. Without knowing that there is no way to tell the total resistance.