`hm-post-repeat` meta is added to both Repeating and Repeat posts

The Repeating (aka main) post should have `hm-post-repeat` meta key with the value of repeat schedule (daily, weekly, etc).

The Repeat (aka clone) post **should not have** that meta key.

However, when creating a post and setting it as a repeat post and saving it; both Repeating and Repeat post have got `hm-post-repeat` meta key.