gwt owner

Does anyone have proof or experience that having similar sites on one GWT account hurt each other in rankings? Example: site1.com/phone/apple (ranking for Apple phones) site2.com/phone/apple (ranking for Apple phones) Since the two domains are on the same GWT and the pages are very similar...

i had a website in my webmaster tools (as owner).also i defined other users for access to my Website GWT.(restricted access) then remove my website from main GWT account (owner).but other users still have access to my site in their webmaster tools. i want to create and verify my website in GWT...