dual voice coil subs, history? invention?

This question "may" or "may-not" require an Old skool Audiophile to answer the question, to include additional info regarding a SUBS time line...My friend claims that way back in 1991 he bought and installed, a pair of 12" Cerwin Vega subs that were DVC's (Dual Voice Coils) Dual 4ohms. I couldn't believe this. I thought about those early years, around the same time frame of: MTX Terminators, Road Thunders, Blue Thunders, etc...I mainly disagreed because back in 1993, I lived around the Ausin area & remembered the Audio setup I had for The Texas Heatwave #4 Carshow, where I took a 1st Place in the Show Category (although I did not compete in the Audio/Sound-off portion), I remember I had (4ea) 12"subs (sealed) and they were all SVC's (Single Voice Coil)...and I was running one of the Newest (although not the best at that time) The MTX  RTA-Line Series Amplifiers.

Anyways, I don't remember anyone around that time frame 1991-1993, in which other people had DVC's subwoofers. This same time frame is when I recall seeing my first ISOBARIK configuration, and thus I changed my sealed sub-enclosure to a professionally built ISO configuration tuned bandpass. Does Anyone else have other INFO that they could provide -or- share so I can determine whether or not he is lying.  Also, If anyone could also provide the information regarding the First Introduction -or- Start of popularity with the use of (SVC's) Subs in an ISOBARIK configuration enclosure vs. Intro to DVC's. And the reason for the lack-of popularity on having an ISOBARIK configuration, (pro's and cons) nowadays... I haven't been back into car stereo until last year or so, so anything new would help. The last amp I last bought that was considered Brand New (at the time) was the XTANT 603x ($1,000) and the still preliminary specs/technical data for the JL W7 were being reviewed,  back in 2000 or so...

So I may be OLD SKOOL , but I really need some NEW SKOOL input and info... 

I think that BIC, the turntable company, was the first company to produce such a driver.  Late 60s or early 70s.

The original purpose was to produce stereo information out of a single driver.

...Let me first apologize for my "dribble - drabble" post. Now getting to the "nitty - gritty" Question...  What is the first DVC (Dual Voice Coil) subwoofer that someone could have used -or- that may have used -or- one that was available in the 1990's ('90 - '94). 

If there is anyone who was alive in the early 90's -and- who has car audio knowledge from that era, pls. respond. If not, I'll consider that either #1)  The majority of the members on this forum are some what "New" (with less then 5 yrs. of audio history and familiarity) -or- #2)    Noboy actually knows. OK, Let's try this...to all readers... Please Post your answer to this question:

Name the Dual Voice Coil woofer that you first either. . .  Installed, Noticed, Saw in a store, Read About, Bought, Heard, Seen, Owned, Blown, or have Stolen.... 

...I don't believe that my friend claims to have owned a pair of Cerwin Vega DVC's in 1991.  There's no way, he could have, I don't believe they were around then. So Readers name your first DVC. 

Cerwin Vega has made DVC subwoofers since the 70's for movie theaters.  CV Stroker car audio subs were available as DVC by the late 80's.  I don't know who invented the idea of using a dual voice coil but if I had to guess I'd say either RCA or Altec-Lansing in the 1940's.  In the late 80's through 1991 I competed for Blaupunkt and used DVC subwoofers.

edit - the BIC reference above may indeed be correct.

I always thought of people using a resistor on the 2nd coil to change the Q of the driver?