i have created a cross platform app using xamarin.forms. i added some toolbar items to some pages but the problem is that they appear twice as in the following picture. 
this is the code of ny page:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="ALNahrainAlphaApp.Accounting"
xmlns:images="clr-namespace:ALNahrainAlphaApp;assembly=ALNahrainAlphaApp"
xmlns:ios="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
ios:Page.UseSafeArea="true">
<ContentPage.ToolbarItems >
<ToolbarItem Order="Secondary"
Text="logout"
Priority="2"
Clicked="ToolbarItem_Clicked"
/>
<ToolbarItem Order="Secondary"
Text="View Total Income"
Priority="2"
Clicked="ToolbarItem_Clicked_1"
/>
</ContentPage.ToolbarItems>
<ContentPage.Resources>
<Style TargetType="Grid">
<Setter Property="VisualStateManager.VisualStateGroups">
<VisualStateGroupList>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="Selected">
<VisualState.Setters>
<Setter Property="BackgroundColor"
Value="#f4f0ec" />
</VisualState.Setters>
</VisualState>
</VisualStateGroup>
</VisualStateGroupList>
</Setter>
</Style>
</ContentPage.Resources>
<ContentPage.Content>
<AbsoluteLayout Padding="0" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
<StackLayout BackgroundColor="White" AbsoluteLayout.LayoutBounds="0, 0, 1, 1" AbsoluteLayout.LayoutFlags="All">
<StackLayout HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand" >
<SearchBar HorizontalOptions="FillAndExpand" x:Name="search" TextChanged="search_TextChanged"/>
<RefreshView x:Name="refresh" >
<CollectionView x:Name="registeredstdslist" SelectionChanged="registeredstdslist_SelectionChanged" SelectionMode="Single" >
<CollectionView.Header>
<Grid Padding="2" ColumnSpacing="1" RowSpacing="1">
<Grid.RowDefinitions>
<RowDefinition Height="35"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="0.4*"/>
<ColumnDefinition Width="0.5*"/>
<ColumnDefinition Width="0.5*"/>
<ColumnDefinition Width="0.3*"/>
<ColumnDefinition Width="0.2*"/>
<ColumnDefinition Width="0.3*"/>
</Grid.ColumnDefinitions>
<Label
Grid.Column="0"
Text="StdID"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
/>
<Label
Grid.Column="1"
Text="Name"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
/>
<Label
Grid.Column="2"
Text="Expected Date"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
/>
<Label
Grid.Column="3"
Text="Edlevel"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
/>
<Label
Grid.Column="4"
Text="Grade"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
/>
<Label
Grid.Column="5"
Text="Status"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
/>
</Grid>
</CollectionView.Header>
<CollectionView.ItemTemplate>
<DataTemplate >
<Grid ColumnSpacing="1" RowSpacing="0" Padding="9,0,0,0" >
<Grid.RowDefinitions>
<RowDefinition Height="40"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="0.4*"/>
<ColumnDefinition Width="0.5*"/>
<ColumnDefinition Width="0.5*"/>
<ColumnDefinition Width="0.3*"/>
<ColumnDefinition Width="0.2*"/>
<ColumnDefinition Width="0.3*"/>
</Grid.ColumnDefinitions>
<Label
Grid.Column="0"
Text="{Binding stdid}"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
FontSize="13"
/>
<Label
Grid.Column="1"
Text="{Binding name}"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
FontSize="13"
/>
<Label
Grid.Column="2"
Text="{Binding ExpectedDateofPayment}"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
FontSize="13"
/>
<Label
Grid.Column="3"
Text="{Binding edlevel}"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
FontSize="13"
/>
<Label
Grid.Column="4"
Text="{Binding grade}"
TextColor="Black"
VerticalOptions="Center"
HorizontalOptions="Center"
LineBreakMode="TailTruncation"
Padding="10"
FontSize="13"
/>
<Image
Grid.Column="5"
VerticalOptions="Center"
HorizontalOptions="Center"
HeightRequest="20"
WidthRequest="20"
>
<Image.Triggers>
<DataTrigger TargetType="Image" Binding="{Binding status}" Value="false" >
<Setter Property="Source" Value="{OnPlatform Android=redtik.png,iOS=redtik.png}"/>
</DataTrigger>
<DataTrigger TargetType="Image" Binding="{Binding status}" Value="true" >
<Setter Property="Source" Value="{OnPlatform Android=greentik.png, iOS=greentik.png}"/>
</DataTrigger>
</Image.Triggers>
</Image>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
</RefreshView>
<StackLayout VerticalOptions="EndAndExpand" HorizontalOptions="FillAndExpand" Orientation="Horizontal" BackgroundColor="#0d98ba">
<StackLayout Style="{StaticResource ButtonNavigationBarStackLayoutStyle}" x:Name="stckAddStd">
<Image Margin="0,10,0,5" x:Name="imgAdd" Style="{StaticResource ButtonNavigationBarImageStyle}" />
</StackLayout>
<StackLayout Style="{StaticResource ButtonNavigationBarStackLayoutStyle}" x:Name="stckfilter">
<Image Margin="0,10,0,10" x:Name="imgfilter" Style="{StaticResource ButtonNavigationBarImageStyle}" />
</StackLayout>
<StackLayout Style="{StaticResource ButtonNavigationBarStackLayoutStyle}" x:Name="stckshare">
<Image Margin="0,10,0,10" x:Name="imgshare" Style="{StaticResource ButtonNavigationBarImageStyle}" />
</StackLayout>
</StackLayout>
</StackLayout>
</StackLayout>
<ContentView x:Name="popupLoadingView" BackgroundColor="Transparent" Padding="10, 0" IsVisible="false" AbsoluteLayout.LayoutBounds="0, 0, 1, 1" AbsoluteLayout.LayoutFlags="All">
<StackLayout VerticalOptions="Center" HorizontalOptions="Center">
<StackLayout Orientation="Vertical" HeightRequest="150" WidthRequest="200" BackgroundColor="Transparent">
<ActivityIndicator x:Name="activityIndicator" Margin="0,50,0,0" VerticalOptions="Center" HorizontalOptions="Center" Color="Black" WidthRequest="40" HeightRequest="40" ></ActivityIndicator>
</StackLayout>
</StackLayout>
</ContentView>
</AbsoluteLayout>
</ContentPage.Content>
</ContentPage>
in android nothing is wrong. but for some reason, in ios, the toolbar items are repeated. any suggestions. thanks in advance.