If for some reason you need to copy blog data from one database (DB1) to another (DB2), please follow these steps:
1. Make sure that Magento 2 instance that uses DB2 has the same blog extension version as one that uses DB1. If not please upldate Magento 2 blog module on one of them.
2. Create a backup of magefan_blog_* tables in DB2.
3. Remove all magefan_blog_* tables from DB2.
4. Make export (dump) of all magefan_blog_* tables from DB1
5. Import dump to DB2.