Not a second wax ring - but a second ring to mount the bolts in. (I would remove the first ring.)
So to restate the levels of material from the floor joists up -
Lead drain pipe/Subfloor/flange(Mounting Ring that will be removed)MortarTileNew mounting ring
The question is - what goes between the new mounting ring and the drain pipe to keep water from getting between the layers of flooring?
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