Is This ½ D ,1902 , KeVII Stamp With A Precancel Or A Overprint ?

There is a extra text printed on this SG O48 ,1902 ,KEVII stamp. Is this a precacel ,overprint, fantasy issue or did someone tried to forge the stamp for some unknown purpose ?
There are few more a have managed to see at the collection of a fellow philatelist .They too show traces of being used as the one on the image.

@post_pe,

There are two things going on here. - I refrain from any opinion on whether these are genuine -.

Stamps with 'OFFICIAL' overprints were stamps prepared for use by certain government departments. As that overprint says, they were official stamps. You will find these for the ARMY, I.R. (inland revenue), R.H. (royal household), Govt. Parcels (government parcels), Admirality, and I may have left some out.

The I.R. OFFICIAL should not be confused with revenue stamps. They were not used as proof of payment, but as a frank by the regional offices of the inland revenue. Departments did not pay postage. The stamps were used for accounting reasons. You will find these stamps on Queen Victoria surface printed stamps and the early (De La Rue) King Edward VII stamps.

The second thing that is going on is a diagonal 'CANCELLED' mark. These were applied when a stamp was used as a specimen, proof, etc. and were not to be used for mail.

Used cancelled stamps cannot exist. As the word 'CANCELLED' indicates, the stamp was cancelled.
Used official stamps exist.
Cancelled official stamps also exist.
Official, cancelled, and cancelled official stamps are listed by Stanley Gibbons.

Some of mine:

NSK,

Thank you ,for sharing a image from your collection. I could see from it tath there is no such text printed on them. It's possible tath the "CANCELLED"mark might have been placed there some time afther the "OFFICIAL" overprint was prepared. It's odd why would someone bother to put this marking on a used stamp when it would be more valuable in mint condition. The other two stamps I have seen are also used. The owner classified them just as undocumented.
The other strange ting for me is the color of the marking . Isn't it in wrong color ? I look trough other stamps with "CANCELLED "markings and they didn't have a marking in purple. It also looks me bit little smudged ,could this indicate tath it could be a handstamped not machine made ?
There are traces of the same cancel marking on the back of the stamp.
I'm posting the back of the stamp to see:

The purple may be due to degradation of the ink. But the most likely explanation is that someone decided to have fun with a phantasy handstamp.

(Good that you reminded me.) I checked my Specialised and no 'CANCELLED' overprint is listed for this stamp. The type also does not fit the period for this stamp.
It is fake.

I am not sure the was used. It, actually, appears unused. The black perforation tips may be due to bad storage.
I am not even trying to understand what people thought when they decided to create a very rare unlisted stamp. But my guess is they weren't doing it to promote philately.

NSK,

Thank you again,for your help. Now I could be certain that it's just a fake .
Every time I looked at it remained my of something I have seened before. I checked at Stampforgeries website, were there are plenty of Official stamps forgeries,it is interesting tath some are with overprints in the same purple color. I don't know ,but it's possible tath they all have the same origin .