Question about Observable List

I have did something similar below. Basic idea is when I clicked a button, it will change the contents of data, but the displayed data is duplicated now.

    <JavaScript>
        var Observable = require("FuseJS/Observable");
        var data = Observable();
        var nullData = Observable();

        var dataOne = Observable(
        { name: "Fancy Bag" },
        { name: "Bubbly"},
        { name: "Strike!" }        
        );

        var dataTwo = Observable(
        { name: "Apple" },
        { name: "Orange"},
        { name: "Banana" }            
        );

        function dataonebuttonHandler()
        {
            debug_log("Clicked Data One Button Handler " ); 
            data.replaceAll(nullData);
            data.replaceAll(dataOne);
        }

        function datatwobuttonHandler()
        {
            debug_log("Clicked Data Two Button Handler "); 
            data.replaceAll(nullData);
            data.replaceAll(dataTwo);
        }

        module.exports = {
        data : data,
        dataOne : dataOne,
        dataTwo : dataTwo,
        nullData : nullData,
        datatwobuttonHandler : datatwobuttonHandler,
        dataonebuttonHandler : dataonebuttonHandler
        }

    </JavaScript>

    <Button  Height="5px" Alignment="Top" >
        <Clicked Handler="{dataonebuttonHandler}" /> 
        <Text FontSize="15">Show Data One</Text>
    </Button>

    <Button Margin="10,10,5,10" Height="5px" Alignment="Bottom" >
        <Clicked Handler="{datatwobuttonHandler}" /> 
        <Text FontSize="15">Show Data Two</Text>

    </Button>


    <StackPanel ux:Name="showDataPanel" Alignment="Center" ItemSpacing="10">
        <Each Items="{data}">
            <StackPanel Orientation="Horizontal" Padding="10">
                <SolidColor Color="0.9,0.9,0.92,1"/>

                <Text Value="{name}" FontSize="30"/>
            </StackPanel>
        </Each>
    </StackPanel>
</Panel>

Hi! Thanks for reporting this.

Unfortunatel, this bug snuck into the previous release (0.5.3166), but is fixed internally.

A new release containing the fix will be out very soon!