Two is even too small if the person can write as many as he or she can let them do it. Because the two copies can also be misplaced or lost. So having more might save the disappointment and lost of coins. I have five copies in different places. I didn't keep them in one place, I heard one in my father's house, another in my mother's house, one is in my office and two are with me.
The two I kept with me are the original but the other ones, I changed one particular figure in all which I know it in my memory. And it is on the first later for all. That is the different between the ones that are with me and the other ones.
You can also go to parenting press or print it with a HP Laptop printer 🖨️ to print it and laminate it so that the laminating paper will become a water resistant to the seed paper.
It's interesting but how have you been able to change the first letter of your seed? Some words of the BIP39 dictionary are exactly the same except their first letters? If it's true, you are not afraid than the guy finding your seed could be aware of those special words, spot them in your seed and try to make the swap of the letters? Especially if your fake seed doesn't contain any transaction?
And if the modified words don't belong to the BIP39 wordlist you're not afraid that the attacker will spot them instantly when he will try to enter them in a wallet? You don't think he could try and manage to find the original word?