Having installed OSX 10.5.2 and Xcode 3.0, I attempted to build a current development project that had built successfully the day before under OSX 10.4.11/Xcode 2.4.1.  The build failed with an error message:
  "Command / Developer/usr/bin/gcc-4.0 failed with exit code 1" 
along with Linking error statement:
  "Id: duplicate symbol .objc_class_name_xxxx in /Users/Shared/Data Files/
   Development ƒ/Cocoa/NNN/build/NNN.build/Development/NNN 2.build/
   Objects-normal/i386/xxxx-3AA85772.o and
    /Users/Shared/Data Files/Development ƒ/Cocoa/NNN/build/NNN.build/Development/
   NNN 2.build/Objects-normal/i386/xxx-3AA85772.o".
Apparently, the linker is seeing two references to the same Class.
I then did a "Find in Project" search for the class name xxxx and it found:
  - two references to "@interface xxxx:yyyy" pointing to same line in xxxx.h code,
  - two references to "#import xxxx.h" pointing to same line in xxxx.m code, and
  - two references to "@implementation xxxx" pointing to same line in xxxx.m code.
Apparently, the Xcode finder uses the same two references to the same Class.
This behavior only affects the xxxx class.  I did similar finder searches on several other classes with yyyy as their super class without any double references.
It would appear that Xcode (or gcc-4.0) has a bug.  My questions are: has this been seen by others, and iwhat is a good fix or work-around available?
Don Thompson