system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why the encryption strength will not increase when an encrypted message gets encrypted again?
gpt
If you use 2 different kinds of encryption, it will strengthen. 

If you use 2 layers of encryption that works off the same algorithm, instead of requiring 2 passwords to solve (as you would expect), there is actually a third password that will solve both encryptions at once. 

Pretend you encrypt a message that shifts every letter 5 letters over in the alphabet. Then you layer a second version of that that shifts all letters 3 letters over in the opposite direction. 

Instead of decrypting by having to shift 5 forward and then shift 3 back, you could just shift 2 forward and unencrypt the message.