Well, I just tried an experiment.
Sometimes when I grab my cutlass to vape, I also grab my backup mod and take a hit off both of them at the same time.
I finally grabbed an A7, cut out two coils from a coil string and left them long and measured them out to about 4 ohms in length, which is about the full length of the coil wire. Wrapped the excess in a couple more loops around the wick, then I carefully mounted both of them in the A7 being careful not to short out the coils and managed to stuff all the wick inside.
I then measure the ohms at about 1.2 ohms when I put it together so I opened it up and found one coil touching the center post. Moved it up a bit, put it back together and measured 1.9 ohms. Just about exactly what I had hoped for.
Squonked till it was slightly gurling and WOW! Dual coils and running great. It does get hot pretty fast though and I would suspect I am gonna really go through the juice and batteries, but what a heavy hit its giving now.
So dual coils in a A7 ERA does work, just have to be careful getting it all in there