Find a cloned element by it's original DOM reference element

Question

I have a <template> with several child elements in it. I'm cloning these child elements via .cloneNode(true) and appending them to document.head.

<template id="my_template">
    <script>
    // …
    </script>
</template>

var template=document.getElementById('my_template');
document.head.appendChild(template.content.cloneNode(true));

What I want

Is there a way to tell at any given moment whether document.head already contains the <template> contents?

What I tried

• Maintaining a flag e.g. template.setAttribute('data-cloned', 1) works, but is a workaround
• document.head.contains() doesn't work probably because a cloned element is internally different:

  for (var i=0; i<template.content.children.length; i++) {
      document.head.contains(template.content.children[i]); // always false
  }
  

• looping through every template element against every element inside document.head, and comparing them using .is(), or their .outerHTML doesn't seem to be very effective.

I'm using the flag attribute right now, but am curious to see if there is a way to accomplish this by only using the template contents and the document.head without creating attribute or className clutter and/or additionally modifying them. I would like to avoid relying on jQuery as long as it's possible and reasonable.