GT Mike, maybe I can help clear this up.
To do a two treatment cleaning and rinse you simply do the same two procedures twice. One cleaning cycle followed by one rinse cycle. Then repeat this a second time.
The suggested basic treatment is to add the product to existing dino oil and change the filter when you have sufficient oil life left for the first 1500 mile cleaning phase.
(I didn't do that, I drained the sump, added the A-RX and topped up with dino because I had been using M-1 synthetic and the Chevron Supreme dino was bought for $0.49 a Qt.) Dino is prefered for both cycles as it is more compatible with the polar molecular structure of the A-RX for this process.
This is the first cleaning phase. Drive the 1500 miles that are specified on the instructions/bottle.
Drain the first cleaning phase mix and refill with a new batch of dino oil and add a new filter. Drive 2000 miles for the first rinse cycle and drain the sump.
Install a new filter, the second bottle of A-RX and top with dino oil. Drive another 1500 miles to do the second cleaning cycle.
Drain the second cleaning mix. Install a new filter and fill with dino again. Drive 2000 miles to do the second rinse cycle.
Drain the second rinse oil and replace the filter. This completes the two treatment cycle and you are good to go forward with whatever oil you prefer to use.
I hope that this might help.
I too was a bit confused reading the instructions a long while back when I first landed here and at the A-RX site, but I read here for quite a while before I attempted the procedure and sorted it out from the many posts similar to your's and the knowledgable replies from members here.
Having said this much, I hope that if I've typed something in error someone will chime in to correct me. John