Steps to reproduce:

1. Navigate to Monitoriing -> Maps, create a map and add map element;
2. In Map element configuration dialog add 2 filtering tags:
   1. "Service" + "Contains" + "Zabbix"
   2. "Service" + "Does not equal" + "Zabbix"
3. Confirm changes and Update map.

Result:
Error with following message appears:

Map update failed.
error: Invalid parameter "/1/selements/1/tags/2": value (tag, value)=(Service, Zabbix) already exists.

Expected:
Uniqueness check should fail only when all 3 properties (tag, operator, value) matches.