Blender, thank you for this.
Your initial concern over this incident also raised my own concerns - hence my enquiry.
What (please) is the standard procedure in a twin .. shut down the overspeeding engine and land with the assistance of the remaining one?
Is there a 109 mechanic who could elaborate on the engine control components most likely to 'clog up' and what pre-flight precautions (if any) can be taken to alert of systems/component failures capable of inducing an overspeed.