If I subscribe multiple collections, which one appears in blaze?

If I subscribe multiple collections:

Meteor.subscribe('categories');
Meteor.subscribe('tags');

That all have the same attribute (e.g., ‘dateCreated’), and I use that attribute in a blaze template,
which value will appear?

<h1>{{dateCreated}}</h1>

You need to create a helper to pass the data to Blaze. Try this:

HTML

<template name="myTemplate">
  {{#each tags}}
    <div>{{dateCreated}}</div>
  {{/each}}
</template>

JS

Template.myTemplate.helpers({
  tags:function(){
    return Tags.find()
  }
});