Encryption with two meanings without computer or programming
This is possible, and it's called deniable encryption. The idea behind this type of encryption is that if you are required (e.g., under subpoena) to provide a key to decrypt your ciphertext, then you can provide an "alternative key" that decrypts it to something else. 

However, this is complex, and you cannot do it by hand. In general, it's difficult to do, even by machine.