Kenwood K20MSS10E microwave oven and double power specification in Watts

[Kiriakos GR]

I am fresh owner of Kenwood K20MSS10E microwave oven (used and repaired by my hands).

The electrical information's about it mention 800W microwave, but by measuring consumption with my (low cost) plug-in power meter, the measurement was up to 1300 Watts.

Google search did not helped me to find more about K20MSS10E Energy Class.

But by paying more attention at Kenwood microwave Users Manual, I did find something interesting.
Kenwood deliver power specifications for the Microwave unit alone, and this is 800 Watts  / 2450 MHz / 230V 50Hz.
The above is named as output power.

But there is and another specifications field, this named as input power.
And this is actually 1270 Watts.

About personal feelings, I do now feel relaxed, my repaired microwave oven, this it does operate according to Kenwood power consumption specifications. 

But until to find of how this double power specification in Watts, actually translates to?
I had a moment about feeling insecure.