Flexipage more than one item identifier

Question

I have a flexipage and delpoy it to an org with unique identifier. But when i am trying to change some value in my component and update flexipage it gives me error : "There is more than one instance identifier with the same name"

What is the problem?

<flexiPageRegions>
    <itemInstances>
        <componentInstance>
            <identifier>Id</identifier>
            <componentName>Name</componentName>
        </componentInstance>
    </itemInstances>
    <name>content</name>
    <type>Region</type>
</flexiPageRegions>