fullname AND flexipage

Question

Why do we have to specify the tag in flexipage packages? How would multiple flexipages show ?

ref: https://developer.salesforce.com/docs/atlas.en-us.api_meta.meta/api_meta/meta_flexipage.htm . Looked at the Metadata definition for fullName as well

<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
    <fullName>New Opportunity Page</fullName>
    <types>
        <members>New_Opportunity_Page</members>
        <name>FlexiPage</name>
    </types>
    <version>49.0</version>
</Package>

Answer 1

You've misunderstood the example. What you're looking at here is a Package that has the name "New Opportunity Page" and includes one element, the FlexiPage called New_Opportunity_Page. If you have multiple FlexiPages, you can deploy them all at once. The UI will also show this as a package that can have components added/removed, and downloaded as an entire unit for deployment to another org.