ohm question

You would be making each sub 1 ohm.  To put two 1-ohm subs together, you can't maintain that 1 ohm load, so you will end up with 1/2 ohm the way you are describing.  The normal way is to arrive at a 2 ohm load with two DVC 2 ohm subs.

If you want to get 1 ohm out of two subs, get DVC 4 ohm models.

I talked to a car stereo guy and he said the L712s dvc 4's cant handle a 1 ohm load.... he said get dual 2's... but I dont know how to wire them... thats why, Im thinkin, instead of paralleling the subs and voice coils, like the picture... just parallel the voice coils and run both subs back to the same terminal

......dude.......I AM a car stereo guy.  He was telling you about one sub.  Look over the wiring diagrams I showed you a link to and come to your own conclusion.

And....running two wires to the same terminal is the same as paralleling the subs together.  Parallel connections are all pos to pos and all neg to neg.  It can take place either on the subs or at the amp, but it's parallel connecting either way.