title: Cannot add extension with name 'kotlin', as there is an extension already registered with that name
body: <p>Having both Gradle plugins gave me that error:</p>
  
  <p>build.gradle.kts</p>
  
  <pre><code>plugins {
      id("kotlin")
      kotlin("android")
  }
  </code></pre>
  
  <p>just either one is fine</p>
  
  <p>Why?</p>
  
  <p>Are they same thing?</p>
  
  <p>I know <code>kotlin("android")</code> is actually <code>id("org.jetbrains.kotlin.android")</code> from the source code of /gradle-6.0.1/src/kotlin-dsl/org/gradle/kotlin/dsl/KotlinDependencyExtensions.kt</p>
  
  <p>but I know nothing about <code>id("kotlin")</code></p>
  
  <pre><code>An exception occurred applying plugin request [id: 'org.jetbrains.kotlin.android']
  &gt; Failed to apply plugin [id 'org.jetbrains.kotlin.android']
     &gt; Cannot add extension with name 'kotlin', as there is an extension already registered with that name.
  </code></pre>