Some daft bint is attempting to cover her tracks.
Proper IT savy PA's will mess with the system clock so the creation date will be correct then stick a footer on it saying dupicate copy.
As a note to yourself don't send word docs back. It is very easy to tamper with them. Always send PDF files and create you own reference numbering system for all correspondance. eg gas/2010/0119 or gas/2010/001 and always ref to that when you refer to a previous letter. It will ring warning bells that a lawyer has told you the system for a complaint to there regulator.