Duplicate Symbol _OBJC_CLASS_$_LoginController

I know this Question has been asked many times before, but none has solved my problem uptill now. I know that this error occurs when you got multiple copies of your file in project. I tried to clean the build, delete any LoginController.m file in Compile Sources and then build. Fine - no errors. When I added my LoginController.m file in Complie resources, compiler again gave the same error.

Next I what I tried is delete all .m files from Compile Sources, clean and rebuild successfully, and added each .m file very carefully. Again same error has been raised. I did not find any duplicate file, then why the heck is this happening?

Please someone guide me. Thanks alot.

EDIT: Error is:

Ld /Users/svp/Library/Developer/Xcode/DerivedData/TryAgain-dhbbyywxclvxfodbunqysmmfefcl/Build/Products/Debug-iphonesimulator/TryAgain.app/TryAgain normal i386 cd /Users/svp/Desktop/TryAgain setenv MACOSX_DEPLOYMENT_TARGET 10.6 setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin" /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang -arch i386 -isysroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk -L/Users/svp/Library/Developer/Xcode/DerivedData/TryAgain-dhbbyywxclvxfodbunqysmmfefcl/Build/Products/Debug-iphonesimulator -L/Users/svp/Desktop/TryAgain/TryAgain -L/Users/svp/Desktop/TryAgain/../CorePlot_1.0/Binaries/iOS -F/Users/svp/Library/Developer/Xcode/DerivedData/TryAgain-dhbbyywxclvxfodbunqysmmfefcl/Build/Products/Debug-iphonesimulator -filelist /Users/svp/Library/Developer/Xcode/DerivedData/TryAgain-dhbbyywxclvxfodbunqysmmfefcl/Build/Intermediates/TryAgain.build/Debug-iphonesimulator/TryAgain.build/Objects-normal/i386/TryAgain.LinkFileList -mmacosx-version-min=10.6 -Xlinker -objc_abi_version -Xlinker 2 -ObjC -all_load -fobjc-arc -D__IPHONE_OS_VERSION_MIN_REQUIRED=50000 -framework MediaPlayer -lz -framework AVFoundation -framework MobileCoreServices -framework SystemConfiguration -framework CFNetwork -framework QuartzCore -framework UIKit -framework Foundation -framework CoreGraphics -lCorePlot-CocoaTouch -o /Users/svp/Library/Developer/Xcode/DerivedData/TryAgain-dhbbyywxclvxfodbunqysmmfefcl/Build/Products/Debug-iphonesimulator/TryAgain.app/TryAgain

ld: duplicate symbol _OBJC_CLASS_$_LoginController in /Users/svp/Library/Developer/Xcode/DerivedData/TryAgain-dhbbyywxclvxfodbunqysmmfefcl/Build/Intermediates/TryAgain.build/Debug-iphonesimulator/TryAgain.build/Objects-normal/i386/LoginController.o and /Users/svp/Library/Developer/Xcode/DerivedData/TryAgain-dhbbyywxclvxfodbunqysmmfefcl/Build/Intermediates/TryAgain.build/Debug-iphonesimulator/TryAgain.build/Objects-normal/i386/Navigator.o for architecture i386 Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang failed with exit code 1

Your error message says that the binaries created from both LoginController.m and Navigator.m define an implementation for your LoginController class. It sometimes happens that this is because of a shared header file that contains implementation logic. Check your Navigator.h/.m for references to a LoginController.