I'm afraid the solution is to have separate IDs for each phone. Your Windows phone automatically syncs contacts with the Contacts stored in People at Outlook dot com. The only way to have different people on each phone is to have different people in Outlook.
If you set up Account A on one phone and Account B on the other phone, you can add the Account A email as a secondary account on the phone with Account B, and vice versa. The contacts from both will appear in the People hub, but if you look at the top, right below the people heading and contacts subheading, you'll see a link that says showing... Set the checkboxes to see only the contacts from Account A on one phone and Account B on the other phone.
Alternatively, you can create groups in the People hub that would allow you to select contacts that you want to appear in List A and contacts you want to appear in List B. You can even pin the groups to the Start Screen for easy access. For more information about that, go to How-to on the Windows dot com website and click on People (in the 4th column below the graphic heading).
I apologize for not providing links. The WPC Ask a Question forum does not permit links due to problems they've had with spammers.