Saudi Arabia Stamps Cut Corner 0.00 Value Meter Stamp Over T

Helloello, Here is a cut corner with two Saudi Arabis stamps. Over the top of them is a red meter stamp with no value. It is about as perfectly placed as you could want and makes me think it was don intentionaly. My question is Why a zero value and was it done simply for the purpose of a collectible?It may be an obvious and simple answer but I don't understand it and little things like this bug me until I find out a plausible reason. Does anyone have an idea why this would be done/\Thanks David

Guess?
meter impressions prepay postage and indicate postage,
in this case gummed stamps have been used,
the machine value set at zero and the meter
used to cancel the stamps.

Thank rod222. It's interesting they would use the meter as a cancel and I like the fact they did it.Although I'm sure it happened a lot, for me it's a unique item for my collection.
Many thanks
Daviv