Safes can keep important information like part of a dual control password, smartcards and pendrives, and so on.
What would be the best practices to prevent loss or damage to a physical locks to a safe? The same question for loss of access password?
Dealing with physical locks is pretty straightforward. You call a professional locksmith and they can open the lock. Once it's open, you can either reset the combination or re-fit a new lock. The bigger and more expensive/professional the safe, the more costly/difficult it is to do this.
Standard practice is to keep a few spare copies of the key in trustworthy places. Tamper-evidence (e.g., envelope, in-case-of-emergency-break-glass, or whatever) is sometimes helpful.
Interestingly enough, physical keys can be duplicated from information. If you take a good picture of a key, the key can be reconstructed from the photo. In fact, if you knew that your front door key was a Schlage 24431, you could go to a locksmith and have them use a Schlage blank and create a 24431 key and it would probably work.
But generally you just pick the lock and change the lock if you lose the physical key.