Test host with 2 interface

zabbix agent port 10050

zabbix agent port2 20050

Test item

Item key

modbus.get[tcp://10.6.4.51:502,1,4,13958,3,uint32,mle,0]

Item type

string

Result

First 3x - agent2

Last 3x - agent

netstat -nlp | grep agent
tcp 0 0 0.0.0.0:10050 0.0.0.0:* LISTEN 706361/zabbix_agent 
tcp6 0 0 :::10050 :::* LISTEN 706361/zabbix_agent 
tcp6 0 0 :::20050 :::* LISTEN 992567/zabbix_agent