I've required to put some paths in my posts and I noticed your plugin was removing the backslashes. I'm a developer so I've attempted repair and the fix turned out to be a pretty simple oneliner so I thought I'll contribute it here:
In the "duplicate-post-admin.php" function "duplicate_post_create_duplicate()" line 302:
'post_content' => $post->post_content,
'post_content' => addslashes_gpc($post->post_content),
It would be great if you could use it in the next release.