Steps to reproduce:

1. Create host with item with type Zabbix trapper. (screenshot and template attached)
2. Create on item witch is previously created trigger with multiple event generation. Where is filtered data by regex also create some tags with regex in value. (screenshot and template attached)
3. Send more than one event with same timestamp and different NS.
4. Check in DB history table for item data. This part is correct
5. Check generated events. Some events are not created and some are duplicated. Count of created events looks like same number of messages sends by Zabbix sender.

Result:
Data in history tables is 100% correct. 
Events are created but with wrong messages in events, with wrong tags values, and some events in history tables are complete ignored. Also events are duplicated.

Check screenshot.

Expected:
For each trapper message with NS will be created separate event with correct message data include correct values in tags.