php string - same and yet not the same

[gregoryferret]

Basically I have 2 strings. They are EXACTLY the same string. However, when I do \[code\]if ($a == $b)\[/code\] it says they are different. I print them out, they are exactly the same I see on browser.The string's a password, \[code\]$a\[/code\] can login but \[code\]$b\[/code\] cannot login. What gives? Weird!