Yes they are the maximum height values, but for each face of the weld. Not total reinforcement.
Root and Cap.
For example, if the maximum allowable reinforcement is 1.6mm, that would be for each face of the weld.
When performing Radiographic interpretation, you would take the nominal wall thickness plus the maximum reinforcement for the cap and the maximum reinforcement for the root. The wall thickness plus 3.2mm.
This has been debated heavily in the past.
For anyone who disagrees, I have a B31.3 Code Committee Interpretation to clarify this.