Yep... I've thought about this too.
But after helping people reset their password for the past 12+ years, it's amazing how often they don't know the difference between their Display name and User Name. I've spent tons of time chasing the wrong one to find their account.
Frankly it's easier when the two names are identical. But of course that defeats the possibility of additional security. What you're talking about is sometimes called "Security by Obscurity". But over the years, it's been proven to be not as effective as most other techniques.
One last worthless comment... (ha ha)... you could always tie your Forum to Facebook and then use THEIR login credentials. Go ahead.... I dare ya!!!
ha ha... sorry... it's late.
