It shouldn't matter either way. It's normal for the spot free pressure to read on the high pressure gauge. They could be different brands or just not accurate anymore. I assume the ones tee'd to the tire cleaner lines are tee'd in after the check valve there, otherwise you'd likely have some issues with spot free backing up into your tire cleaner or vice versa.
Correct, the tire cleaner and spot free have been backing up to each other, so I just added a check valve in front of the spot free. But not having a check valve didn't really create any issues like seeing
soap in my spot free tank (I guess it wasn't making its way all the way back to the tank since its low pressure, and it doesn't matter to have spot free in tire cleaner it just makes it a bit watery) . I was seeing a bit of a
soap in the beginning of spot free function, which I still see after adding the check valve (all of my bays do that)
But adding a check valve fixed my other problem which I posted a different note. On this bay I had a dripping issue from the gun. Now with the check valve added on spot free, no more dripping, yey.