I got a strange issue with my site in Magento 18.104.22.168 and I can't understand the reason.
Sometimes I got sales order notification sent 2 or 3 times, sometimes even after a few hours away from the first email.
In core_email_queue_recipients I can see different message_id but same recipient_email but in core_email_queue table I can see the same entity_id and I can't figure why this happens.
Cron configuration is tested and work well I can't understand why this issue occurs.
Does anyone have any idea?
Thanks in advance