Floating Action (Button Problem) New User Sign Up

[lugems]

Floating Action Button +@id/fab on click after compile and running on the phone doesn't work
and two floating action buttons have the same id (+@id/fab) both in activity_login.xml

<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignEnd="@id/cv"
android:layout_alignTop="@id/cv"
android:layout_marginEnd="20dp"
android:layout_marginTop="25dp"
android:onClick="clickRegisterLayout"
android:src="@drawable/ic_signup"
android:transitionName="loginFab"
app:fabSize="normal"
android:layout_alignRight="@id/cv"
android:layout_marginRight="-20dp" />

and activity_register.xml

android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal top"
android:onClick="clickBackLogin"
android:src="@drawable/plus_x"
android:transitionName="loginFab"
app:fabSize="normal" />