Certain campaigns, when exported, produce a xml file that is really large (some are up to 70MB), even if the campaign doesn't have that much content or attachments. The reason is the current export logic, instead of using the wordpress function to get the metadata, uses a select on the metadata table that gets all the records for a certain post/attachment. However, due to some other bug, there may be many duplicate records in that table, up to thousands for certain attachments. All these duplicate records are currently exported and also created on import.

TASK: in exporter.php, replace the database query with a call to the wordpress function "get_post_meta", which only returns distinct records.