I took more pictures and I think I am in the camp of Cetol or something still on the rails in the area of the stripes.
First here is a prior (actually the strbrd side, but the port looked similar)
What I noticed is that I can see the same types of stripes under the old Cetol. So maybe it is something left from a prior staining, that they never removed (or couldn't?).
Here is a portion of the Port side stripped and sanded.
It does look like the rub rail has some stain more uniformly left on it, that may not bother me to much. But I have to do something with the toe rail.
I purchased some Oxalic acid to try on an inside rail area, I will see if that helps.
At least the handrails are coming out clean.