I purchased above two items at an auction in 2006, they were described as "wrappers overprinted SPECIMEN which were affixed to a
placard to inform the Indo-China public of their existance. Ex Wallberg collection."
The 2c wrapper is 52mm x 299mm and the 3c is 52mm x 302mm. Both of them are glued to another paper.
When I asked the auctioneers for additional information all they could tell me was "This information was written on a note included
by the vendor, which we believe to be correct since he was an avid collector of this area."
Over the next ten years I made many enquiries about this item to no avail.
At a meeting of The Postal Stationery Society in March 2016 James Bendon displayed a sheet with postal stationery and stamps as shown in the illustration below.
This sheet was issued by the Post & Telegraph Administration of Indo-China in 1889 to be displayed in their post offices.
The sheet size is about 620mm x 775mm.
So finally I had confirmation that these did come from Indo-China and could see how they were originally shown.