Narrow TVS margin between operating and overvoltage
The reason why the absolute maximum Vcc on the pins is Vcc+0.3V is because above that voltage, the internal clamp diode to Vcc will turn on -- as long as there's a series resistor between the I/O pin and outside world to limit that current to what the clamp diode can handle, it will not permanently harm the IC.  (Modern datasheets give an Iik, Iok, or Ik specification for this maximum current.)

So, use the higher clamping voltage TVS to absorb the bulk of the energy and a series resistor to keep the port pin's clamp diode from being burned out.