title: PrecompiledAssemblyException: Multiple precompiled assemblies with the same name UnityEditor
body: <p>When I imported an asset to unity then I try to run the game this message appeared :</p>
  <p>allowed per platform. Assembly paths: C:/Users/ELEMENT14/MyGameIdea/Library/PackageCache/com.unity.ads@2.0.8/Editor/UnityEditor.Advertisements.dll, Assets/2D Top Down Shooter/2D Top Down Shooter/Library/PackageCache/com.unity.ads@2.0.8/Editor/UnityEditor.Advertisements.dll
  UnityEditor.Scripting.ScriptCompilation.EditorBuildRules.CreateTargetAssemblies (System.Collections.Generic.IEnumerable<code>1[T] customScriptAssemblies, System.Collections.Generic.IEnumerable</code>1[T] precompiledAssemblies) (at C:/buildslave/unity/build/Editor/Mono/Scripting/ScriptCompilation/EditorBuildRules.cs:251)
  UnityEditor.Scripting.ScriptCompilation.EditorCompilation.UpdateCustomTargetAssemblies () (at
  C:/buildslave/unity/build/Editor/Mono/Scripting/ScriptCompilation/EditorCompilation.cs:636)
  UnityEditor.Scripting.ScriptCompilation.EditorCompilation.SetAllCustomScriptAssemblyJsons (System.String[] paths) (at C:/buildslave/unity/build/Editor/Mono/Scripting/ScriptCompilation/EditorCompilation.cs:746)
  UnityEditor.Scripting.ScriptCompilation.EditorCompilationInterface.SetAllCustomScriptAssemblyJsons (System.String[] allAssemblyJsons) (at C:/buildslave/unity/build/Editor/Mono/Scripting/ScriptCompilation/EditorCompilationInterface.cs:217)
  UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)</p>
  <p>My Unity version is 2018.4.11</p>