There is almost nothing that you can do about this, especially if you have used the same field names for the fields. You would need a list of all of the post IDs that have the wrong data and you’d have to delete the meta fields for those post IDs.
The only real solution is to delete all of the posts that exist. (trash and then delete permanently). This will cause WP to delete all associated meta fields.
And then start over with the fields that you want to keep.
