Depends on how you do the sums from the AFM.
MTOW is a hard limit regardless of other considerations and is tied up with the basic aircraft certification basis.
RTOW is the limiting takeoff weight calculated for a particular runway under particular specified conditions.
Generally, though, the published RTOW will be truncated for other limiting considerations for convenience.
Usually the only time you might see a performance weight greater than MTOW will be in relation to climb limits where the calculated figure is given to facilitate interpolation - it doesn't make much sense to interpolate between figures where one has already been truncated due to other limits. In this situation the interpolated figure then is compared to other limits in the normal manner to determine the overall limiting figure.
Either way, the authorised TOW will not exceed the MTOW (unless per Regulatory one-off approval as, for instance, may occur for ferry operations).