Facebook SDK and Audience Network SDK Android conflict

Hi guys, I am using the Facebook SDK in my project and I want also to integrate Facebook's Audience Network SDK. The problem at first that both SDKs come with Android Support libraries, so when I try to build the project the process breaks when converting from java to dex:

 CommandInvokationFailure: Unable to convert classes into dex format. See the Console for details.
 C:/Program Files/Java/jdk1.8.0_92\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir="C:/Android/sdk\tools" -Dfile.encoding=UTF8 -jar "C:\Program Files\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar" -
 
 stderr[
 Uncaught translation error: java.lang.IllegalArgumentException: already added: Landroid/support/v4/accessibilityservice/AccessibilityServiceInfoCompat;
 ....]

I try to fix this by removing this library from one of the two SDKs, but in both cases I get another error:

 Error building Player: CommandInvokationFailure: Unable to convert classes into dex format. See the Console for details.
 C:/Program Files/Java/jdk1.8.0_92\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir="C:/Android/sdk\tools" -Dfile.encoding=UTF8 -jar "C:\Program Files\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar" -
 
 stderr[
 
 trouble writing output: Too many method references: 65909; max is 65536.
 You may try using --multi-dex option.
 References by package:
      6 android.accessibilityservice
      5 android.accounts
      12 android.animation
 ...... (It keeps going with a long list)

I just have no idea on what is causing this second error. Curiously though, if I remove the library from both SDKs, the project will build, but I guess the SDKs won't work properly.

Any clues?

Thanks!