I am getting an error like this:
[WARN]Warning: Multiple build commands for output file /Developer/B/Be/build/Release-iphonesimulator/BB.app/no.png
[WARN]Warning: Multiple build commands for output file /Developer/B/Be/build/Release-iphonesimulator/BB.app/d.png
[WARN]Warning: Multiple build commands for output file /Developer/B/Be/build/Release-iphonesimulator/BB.app/n.png
But I have checked Xcode and I don't see any duplicates of such files at all. As this post in the Apple Mailing Lists say, there are no duplicates.
This is not a bug. Xcode assists can assist you. Select the target, to the left in the project Navigator. Click on "Validate settings" at the bottom of the settings. Xcode will check the settings and removes duplicates if possible.
This is easily caused when you add git based subprojects. Xcode isn't smart enough to ignore the .git subfolder even though you can't see it from finder, so it will get very confused that there are multiple files named "master" or "exclude", (standard git repo files). With Xcode4, go to the project (root of the left tree) then click your app target and expand "Copy Bundle Resources", then remove all the references to .git, you shouldn't need them baked into your app anyway.
In the Project Navigator, select your Xcode Project file. This will show you the project settings as well as the targets in the project. Look in the "Copy Bundle Resources" Build Phase. You should find the offending files in that list twice. Delete the duplicate reference.
Xcode is complaining that you are trying to bundle the same file with your application two times.
Yet another variation on this issue. I had the same message come up none of the previously suggested solutions solved the problem (I definitely only had one copy of the offending file for instance).
My solution was to edit the project.pbxproj file in a text editor (after quitting XCode and backing up the file of course) and remove all references to the offending file. Then, after starting XCode again, I manually added the file back into the project and everything was ok.
(My suspicion is that this problem happened to me because of a manual, ie: non-XCode, merge of the project file.)
For me the Target > Build Settings > Packaging > Product Name was set to the same thing as another value referenced in a .plist file which was custom to my app. Eventually due to our build process this creates duplicate files.
This happends because ur "no.png" "d.png" and "n.png" are duplicated in resources . Just look for delete dublicated files and delete.