How do I keep double SOME line breaks in wordpress?

Is there any way to force double line breaks to be preserved?

I mean, NOT across the whole site, but just inside a specific container, only in the editor (javascript). The content saved to the post content should be filtered normally.

Do you know of any property or class that could make wpautop not to catch them and preserve them?

Or what part of wpautop should I hack to make it skip the conversion when the BR tags have some class?

I could add the class manually, and I don't need the modified wpautop filter to run in the whole post or in PHP, just in the editor in JS.

Thanks.