android studio - Why do we set Gradle classpath reference in both project's and module's build.gradle? -

When we create an empty Android Gradle project using Android Studio 1.1.0 (and all earlier versions of Android studio) , The two references to the Gradle plugin are in the build.gradle of a reference project and the other reference is in the build.gradle module. And both look the same.

  buildscript {repositories {mavenCentral ()} dependency {classpath 'com.android.tools.build:gradle:1.xx'}}  < / Pre> 
 As I have experienced, the version of the grudge is more important than the project file because I can set it to the latest griddle (v 1.1.3 for Android Studio 1.1.0), while I can leave The version of the griddle (!) In old modules  build.gradle  The project will compile without any error 
 
 So why is the module reference at first place? 
 
 We say that the reason for this is that we can use other grade versions in some modules. Does this mean that I can remove these lines from the module's  build.gradle  if I plan to use the same grade version through this project? In this way I have to update the same line in all the modules. 
 

We do not have to do this! It seems that this habit was present in earlier versions of Android Studios (probably before the official release)

There is only one reference in Android Studio v1.1.0 - the project's build.gradle in

Note: This project was built on the old version of Android Studio (which is not fixed) and its code is inherited.