A metal plate with the words that open a fortune is a key, not a collector's piece for the display case. In the overview Security for collectors, it stands at the edge of that world, because people put it next to coins and then photograph it.
What you do not do
You do not photograph the plate. You do not upload it to a cloud, not into an email, not into a chat window. You do not say the wording in passing. A backup that sits online is not a backup, but a copy for other people.
Where to put it
Fireproof, separate from the computer and from the drawer with the coins, in a place you can find again and that not every guest sees. A second plate, if you keep one, lies in another place, not in the same cabinet. The heirs must know the place, without the wording standing on a note on the refrigerator. The note with the directions does not contain the words.
Fire and loss
A fire that eats paper also eats a poorly chosen copy. Metal survives more than paper. It does not survive heat without limit. You do not put it next to the boiler, and not into the one bag you lose when you travel.