Interesting anecdote. The actual Rosetta stone is in the British Museum in London. It is currently behind glass, you are allowed to take photographs, without the flash.
The first time I saw it was over 20 years ago in the same museum. The difference was that it was on display, with no barrier. Visitors to the museum were permitted to touch and feel the stone, (no it was not a copy, I inquired of one of the docents and was advised that it was the real stone). I wondered to myself the lettering is going to get smoothed off if they continue to let hundreds of visitors touch the damn thing. I guess they decided themselves that it was too much a risk.
The Rosetta Stone of the future, after the world recovers from the zombie apocalypse, will probably be something like a surviving modern DVD Player manual. Finding one of them preserved will be pure gold / zlato / emas / ginto.
And some documents which are in multiple languages are fragmentary: different pieces are in different languages, but they are not translations of each other. The first document known with Spanish writing is hand-written notes on the sides of an illuminated book; the main text is in Latin, there are notes by the same hand in Spanish and in Basque& and one note by a different hand in Latin*, but none of it is translations of anything else so it can’t be used as a deciphering tool.
& It also happens to be the oldest known document with Basque writing.
Which roughly translates to “the book isn’t yours, you son of a pig and a castrated donkey, stop writing on it!”+
The Detroit Institute of Arts has a sculpture that you’re allowed to touch, along with a photograph of the statue as originally built, in order to show the damage that is done by patrons continuously touching something over a long time.
The context to this is that shortly after the Stone arrived in London it was covered with a clear wax coating. The main purpose of this was to allow it to be used a printing block. After all, to disseminate faithful copies of the inscription(s), it was easier to print them directly from the stone, rather than having someone make a copy first. This coating remained in place, so the BM was casual about visitors touching the “stone”, since they actually weren’t.
Matters changed in the early 21st century. Ahead of the (disappointing) special exhibition on Egyptian writing that they held c.2002 to mark the anniversary of it arriving in London, the Stone underwent a comprehensive programme of conservation. As part of which, the wax coating was removed. Once it went back on display after that, initially in the exhibition, but now more generally, it’s always been in a glass case.