Bonus: How to set up Two Blogger Subdomain Names
If you try to set up two blogger subdomain names you might run into the same problem I did. Blogger will not give you the first error code with the two names and destinations that you need to add. Simple solution, enter a main-domain of a website you don't own (subdomain.gibberish.com example make.alskdjfl.com). Gibberish is amazing. Now you can proceed as before but remember to change the main-domain back to the domain you want in blogger before you click save (the second time).