There are a few technical, advanced ways to avoid this by diving into your site’s code.
But otherwise, there’s a really easy workaround.
Just ditch the teaser and stick to blog post titles. That’s what I do on my site:
You can also use canonical tags, which tells Google which post is the original. It’s worth noting that duplicate content is as big of a deal as Google has gotten smarter, but it’s still a good idea to avoid it.