nowadays with digital database of registration in most cities...the actual registration document is just a single page..like in islamabad reg....so its no more a BIG issue, yes the dealer type awaam still exploit the situation when someone is selling such a car and they come up with these retarded excuses to devalue a perfectly alright car.
there are more reasons of the same type lurking around in society like
loss of original number plate
change of registration number
recovery from theft
logically all these things SHOULD not matter but unfortunately they DO. back in those days when registration copy was a manually created document...that HAD to be original otherwise there would most probably be somethin wrong...like a theft recovered car, or somebody tryin to put a stolen car on his name in a different city, computerized registration will solve all these issues in the coming year or 2 i hope.