What endpoint are you using? favorites/list? You can try to set since_id depending on what you’re using it for. Otherwise you’ll have to store the stuff you already fetched and ignore it if it’s already been added.
Yeah, favorites/list. Unfortunately, since_id will not work, as my user could easily favorite a tweet from a later time, even weeks in the past. It’s a fairly common behavior. Right now I have to continuously deep crawl all favorites.
There is no such thing as a favorite id, it’s simply the id of the status, therefore since_id/mac_id are basically nonsensical in context of when the user took the action. There is also no way to get the timestamp of when the action was done (no top level meta data)