I used to think that too - but not so.
The coils are double ended - when the magnetic field collapses around the windings both ends get hot - one positive, the other negative (on a standard ignition the bottom end of the Secondary is tied back to the the primary - like an auto transformer or flyback, which it is.) The coil secondary ends are connected to the plugs - on the companion cylinders.
The coils fire on each TDC stroke for those cylinders - Secondary current goes from one end, through a plug, through the block to the other backwards (reversed polarity,) then back to the coil.
The cylinder under compression is harder to fire - more required voltage needed. The waste spark is relatively easy to fire since it's almost a vacuum at that time.
IF the primary was to alternate polarity, then they each would get alternate charges like seems logical. But since there's only one current source and one polarity primary signal from the PCM they don't alternate.
I'd been told they fired both ways (and assumed,) plus and minus, I was expecting to see it, but since I have a dual trace lab scope now I can see it. It's still hard to see, too difficult to snap a picture of it - I've tried - my cameras just aren't fast enough to get anything but a blur.
The double plats you like are supposed to resist the electrode wear on both center and ground electrodes. It would be interesting to see some single plat plugs that have lots of miles on them - they'll most likely show 3 worn bad and 3 that lived. I haven't been able to see some - yet.
I developed a dislike for plats over the years
- seemed like every time I used them or got involved with poor performance and misfires they had plats. I could see them from across the room on a scope - they always looked fouled! (I just tossed them in the trash - too bad - if I'd saved them for the platinum we could be having this conversation on a beach in Hawaii
. We tossed out lots of them.
Now that was years ago - with conventional Kettering type ignition systems, points or electronic, even CD's.
Times have changed - "my jury" is still out
. It's possible the Jeep ignition has a faster rise time, or more current in the secondary - I have yet to look at that.