title: Duplicate symbol _OBJC_CLASS_$_Facebook
body: <p>I'm building an ARC iphone app, and about to integrate the addThis ios library. </p>
  
  <p>I get the following error:</p>
  
  <pre><code>ld: duplicate symbol _OBJC_CLASS_$_Facebook in /Users/mars/Desktop/Pst/trunk/Pst/ThirdPartyLibs/FBConnect/FacebookSDK/FacebookSDK.framework/FacebookSDK(Facebook.o) and /Users/mars/Library/Developer/Xcode/DerivedData/Pst-bqmphjiqldalzsankfvxugsurcdj/Build/Intermediates/Pst.build/Debug-iphonesimulator/Pst.build/Objects-normal/i386/Facebook.o for architecture i386
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>I've double checked with my Compile Resource, and only 1 facebook.m is present. </p>
  
  <p>I've also put "-fno-objc-arc" in my compiler flags for those library files because they are built without ARC</p>
  
  <p>Any help would be really appreciated!!</p>