Low flange

keep running in to flanges being set below tile 1 regular wax ring will not make a seal is it better to stack some flange rings or just get a jumbo wax ring or double em

It's always better to use flange spacers, doubling the wax can lead to problems if you are talking about a large recess.

This is a pretty common problem that seems to be increasing because more and more folks are installing tile when they remodel their bathrooms. Use the rings because as Shacko stated, thick wax rings can cause problems. The rings will remain solid and are a whole lot easier to install than a new flange.