Merging custom post types from 2 different sites

I have some custom post types on (2) different dev instances of a WP site. In short, what I need to do is merge these custom posts and dedup them, so all the unique posts from each site, wind up on a single site.

I might be able to manually reconcile things, by comparing post_title and post_date between sites. Of course, that’s going to be a lot of work, and I’m not even sure how I’d migrate the missing posts from one instance to the other.

In short, I’m looking for any ideas, on how to most efficiently tackle this. Is there a plugin that can do this kind of thing?

I also considered copying over the posts table from one site to the other, and then trying to do some SQL foo, to get it done. However, I’m not exactly sure what that SQL would look like. In the absence of a better solution, this is what I may try first.

Would appreciate any ideas out there. Thanks!