Cannot Register Myself Twice Because IP is the same?

You either have to wait until someone else registers from a different IP Address or,

Goto the ACP > Cracker Tracker > Settings > Registration Protection System:

Set: Register Protection - Disabled

Set: IP Watcher - Disabled

At the Bottom of the Page - Click "Save Settings"

You will probably have to clean your Browser Cookies and ALL IP Caches so that cTracker "forgets" about you?