Getting error "Duplicate attribute" on second view of constraint layout

Question

I am getting error of "duplicate attribute" on the second view of constraint layout as commented below, it doesn't matter if i place any other view on second position. I am getting the same error. xml code is given below:

<android.support.constraint.ConstraintLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:card_view="http://schemas.android.com/tools"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content">


<android.support.v7.widget.CardView
    android:id="@+id/cardView2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="2dp"
    android:layout_marginLeft="50dp"
    android:layout_marginRight="30dp"
    android:layout_marginTop="2dp"
    android:background="@android:drawable/dialog_holo_light_frame"
    android:elevation="@dimen/cardview_default_elevation"
    app:cardCornerRadius="18dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.0">

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/textView2"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginLeft="56dp"
            android:layout_marginStart="56dp"
            android:layout_marginTop="18dp"
            android:fontFamily="serif"
            android:text="Popcorns"
            android:textColor="@android:color/black"
            android:textSize="26sp"
            android:textStyle="bold"
            android:translationZ="2dp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

  //second view starts from here.
        <RatingBar
            android:id="@+id/ratingBar"
           style="@android:style/Widget.DeviceDefault.Light.RatingBar.Small"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="32dp"
            android:layout_marginStart="56dp"
            android:layout_marginTop="8dp"
            android:numStars="5"
            android:progressTint="#fdd835"
            android:rating="3"
            android:stepSize="1"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView2"
            app:layout_constraintVertical_bias="0.0"
            card_view:layout_editor_absoluteY="39dp"
            tools:layout_editor_absoluteY="63dp" />


        <TextView
            android:id="@+id/textViewWeight"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginBottom="8dp"
            android:layout_marginTop="8dp"
            android:paddingBottom="8dp"
            android:text="280 g"
            android:textSize="13sp"
            android:translationZ="2dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="@+id/textView2"
            app:layout_constraintTop_toBottomOf="@+id/ratingBar" />

        <TextView
            android:id="@+id/textViewPrice"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="4dp"
            android:layout_marginEnd="32dp"
            android:layout_marginTop="8dp"
            android:fontFamily="serif"
            android:text="Rs 100"
            android:textColor="#FF0000"
            android:textSize="15sp"
            android:textStyle="bold"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.86"
            card_view:layout_editor_absoluteX="215dp"
            card_view:layout_editor_absoluteY="54dp"
            tools:layout_editor_absoluteX="216dp"
            tools:layout_editor_absoluteY="56dp" />



    </android.support.constraint.ConstraintLayout>


 </android.support.v7.widget.CardView>

have some other view here

 </android.support.constraint.ConstraintLayout>