From what I understand... your speaker may be a DVC 2 ohm, in parallel creates a 1ohm load. But actually your amp will see a fluctuation of 1ohm during certain frequencies. So at times the amp might play a 30hz freq and see a .75 load any other times it can pop up to 1.25 etc... so its not actually playing 1ohm straight through.
Not to mention, no ones resistance on their sub is 1.00 ohms. I've got an Adire Brahma, DVC 2ohm. Each side actually registers 1.75 ohms on a volt meter.
I suppose this is also a way for the sub to squeeze out a few more watts from an amp, kinda nice.