By default, Duplicate Post copies every custom field except a handful of ones (see below). This option expects a comma-separated list of custom fields names to skip while copying: e.g.
From version 3.1.*, the option accepts the asterisk (*) as a wildcard character, matching zero or more alphanumeric characters (letters and digits) or underscores (_). This means that if the list contains the value
field*, custom fields with names like
field_asd0qwerty will be filtered out during copy.
Duplicate post always skips these custom fields:
_edit_last, which are used by WordPress to prevent multiple users to edit the same post at the same time;
_wpas_mess, which are used by Jetpack module Publicize to keep track of whether a post has already been shared to social networks.
The custom fields copied by Duplicate Post are those stored in the
postmeta table. Every custom meta data stored in non-standard WordPress tables by plugins or theme, though linked to the original post, is ignored, since Duplicate Post can’t know if and where this data is placed and how to clone it. You must use hooks to attach code handling these non-standard metadata.