zabbix_sender utility makes duplicates and send them to Zabbix server. For example:

1. ./test.pl 200 > test2 && ./zabbix_sender -z 192.168.137.22 -p 10051 -T -i ./test2
   info from server: "Processed 250 Failed 0 Total 250 Seconds spent 0.003012"
   info from server: "Processed 250 Failed 0 Total 250 Seconds spent 0.003321"
   info from server: "Processed 100 Failed 0 Total 100 Seconds spent 0.001202"
   sent: 600; skipped: 0; total: 600
2. cat ./test2 | wc -l
   400

We have only 400 records in file, but zabbix_sender sent 600.

It happens only with zabbix_sender installed on Solaris 10/11.