Yes, each new account needs a unique phone number.
You can get two FREE Google Voice Numbers per one mobile phone by doing the following:
1) Create 2 gmail accounts (Or use ones that are already active).
4) On your legacy Google Voice home page, click the gear icon in the top right and select “Settings”.
5) Where it says “Forward calls to: (your phone number)” click “edit” and change your phone type to “work”.
6) Now sign in to your other gmail account and head back to https://voice.google.com.
7) Repeat the steps from above except now you will want to change - this phone type to “home”.
You should now have access to two Google Voice numbers.