Two actionbars when starting ActionMode

I have the following activity layout:

<?xml version="1.0" encoding="utf-8"?>

<android.support.v4.widget.DrawerLayout
    android:id="@+id/drawerLayout"
    style="@style/DrawerLayout"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <android.support.design.widget.CoordinatorLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        tools:context=".ui.activity.MyActivity">

        <android.support.design.widget.AppBarLayout
            android:id="@+id/app_bar"
            android:layout_width="match_parent"
            android:layout_height="@dimen/app_bar_height"
            android:background="@color/black"
            android:fitsSystemWindows="true"
            android:theme="@style/AppTheme.AppBarOverlay">

            <android.support.design.widget.CollapsingToolbarLayout
                android:id="@+id/toolbar_layout"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:fitsSystemWindows="true"
                app:collapsedTitleTextAppearance="@style/ToolbarTitle"
                app:contentScrim="@color/primary"
                app:layout_scrollFlags="scroll|exitUntilCollapsed">

                <android.support.v7.widget.Toolbar
                    android:id="@+id/toolbar_top"
                    android:layout_width="match_parent"
                    android:layout_height="?attr/actionBarSize"
                    app:layout_collapseMode="pin"
                    app:popupTheme="@style/AppTheme.PopupOverlay"
                    app:theme="@style/ThemeOverlay.AppCompat.Light"/>

            </android.support.design.widget.CollapsingToolbarLayout>
        </android.support.design.widget.AppBarLayout>

        <my.package.ui.widget.MyHeaderWidget
            android:id="@+id/deal_header"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_behavior="my.package.ui.activity.MyHeaderBehavior"/>

        <include layout="@layout/content_list"/>
    </android.support.design.widget.CoordinatorLayout>

    <include layout="@layout/navigation_view"/>

</android.support.v4.widget.DrawerLayout>

It is used to have a collapsing toolbar + the navigation drawer + an animation for a title an sub title (in the header widget). Everything is good until I try to start the ActionMode to enable multi-selection.

I do it by calling:

    mActionMode = mCollapsingToolbarLayout.startActionMode(mActionModeCallback);

The problem is that I end having two actionbars (with two arrows):

The black one is the one that I was expecting to be there the white one is added when I start the ActionMode.

Am I doing something wrong?

EDIT

in the AndroidMaifest

    <activity
        android:name=".ui.activity.MyActivity"
        android:label="@string/title_activity"
        android:theme="@style/MyTheme">
    </activity>

In the styles.xml

<style name="MyTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="android:windowBackground">@drawable/window_background_gray</item>
    <item name="android:colorBackground">@color/app_background</item>
    <item name="displayOptions">showHome|homeAsUp|showTitle</item>
    <item name="android:icon">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="colorPrimary">@color/primary</item>
    <item name="colorAccent">@color/accent</item>
    <item name="colorPrimaryDark">@color/primaryDark</item>
    <item name="android:textAppearanceButton">@style/Theme.ButtonTextAppearance</item>
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
</style>

EDIT2

If you want to test this issue you can create a new project in Android studio with the ScrollingActivity sample code. Modify the theme as you think you should and then just start the action mode when pressing the FAB, passing the following object as ActionMode.Callback to startSupportActionMode:

private ActionMode.Callback mActionModeCallback = new ActionMode.Callback() {
    // Called when the action mode is created; startActionMode() was called
    @Override
    public boolean onCreateActionMode(ActionMode mode, Menu menu) {
        // Inflate a menu resource providing context menu items
        MenuInflater inflater = mode.getMenuInflater();
        inflater.inflate(R.menu.menu_scrolling, menu);
        return true;
    }

    // Called each time the action mode is shown. Always called after onCreateActionMode, but
    // may be called multiple times if the mode is invalidated.
    @Override
    public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
        return false; // Return false if nothing is done
    }

    // Called when the user selects a contextual menu item
    @Override
    public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
        switch (item.getItemId()) {
            case R.id.action_settings:
                mode.finish();
                return true;
            default:
                return false;
        }
    }

    // Called when the user exits the action mode
    @Override
    public void onDestroyActionMode(ActionMode mode) {
        mActionMode = null;
    }
};

Solution

If you're using a Toolbar these 3 lines are enough:

 <style name="AppTheme.NoActionBar">
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
    <item name="windowActionModeOverlay">true</item> <!-- This is the important line -->
</style>

Remember to add that in both files styles and styles(v21)