W3C HTML validation errors

I’m using the following code on my FAQs page because I need <h2> headings:

<h1>Frequently Asked Questions</h1>
<h2>Website Design</h2>
[faq-concertina category=”website-design”]
<h2>Content Management Systems</h2>
[faq-concertina category=”content-management-systems”]
<h2>E-Commerce Websites</h2>
[faq-concertina category=”e-commerce-websites”]
<h2>Search Engine Optimization</h2>
[faq-concertina category=”search-engine-optimization”]

Although the page appears to display properly, I’m getting Duplicate ID errors in W3C’s validator (https://validator.w3.org/nu/?showsource=yes&doc=http%3A%2F%2Fwww.noesisdesignstudio.com%2Ffaqs%2F) because the plugin uses IDs rather than classes.

Is there any way to fix this?