How can I save my seed phrase?
I have heard that many people carve their seed phrase on stone. And they use different techniques to save it. If someone else gets 2 or more of my seed phrases, will it harm me? How can I make my seed phrase more secure?
You have a genuine concern if I were to tell you, especially if you have a substantial amount in your wallet. Well, first ensure the security of your wallet, because if you lack in security in it, even the security of the seed phrases will not help you.
Now, you don't need to go through the mile of carving your seed phrases on stones.

My advice: write your seed phrases where you like, but let there be duplicates of at least 2 of them. Here is the catch: you might have 12 words in them, you can write the words with some missing words in those places while you memorise the missing words, or write them in other places.
Still, make it more than one copy in case you forget or misplace it/them.
The problem here with storing the seed phrases on your memory is that it could be dangerous in such a way that if you eventually forget it you've lost access to your funds, except for the fact that the two numbers which you will missed to write that will be stored in your memory will be two stored in two different places.