Ping duplicates

Hi 
can someone advise me...I'me pinging an ip address & I am getting
duplicates back see attachements, what could be the problem.

Rgds.

Harry.

 <<ping.txt>> 

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PING 10.4.72.11 (10.4.72.11) from 10.129.30.79 : 56(84) bytes of data.
64 bytes from 10.4.72.11: icmp_seq=0 ttl=122 time=32.678 msec
64 bytes from 10.4.72.11: icmp_seq=0 ttl=122 time=32.678 msec (DUP!)
64 bytes from 10.4.72.11: icmp_seq=1 ttl=122 time=29.970 msec
64 bytes from 10.4.72.11: icmp_seq=1 ttl=122 time=39.970 msec (DUP!)
64 bytes from 10.4.72.11: icmp_seq=2 ttl=122 time=29.975 msec
64 bytes from 10.4.72.11: icmp_seq=2 ttl=122 time=39.975 msec (DUP!)
64 bytes from 10.4.72.11: icmp_seq=3 ttl=122 time=29.982 msec
64 bytes from 10.4.72.11: icmp_seq=3 ttl=122 time=39.982 msec (DUP!)

--- 10.4.72.11 ping statistics ---
4 packets transmitted, 4 packets received, +4 duplicates, 0% packet loss
round-trip min/avg/max/mdev = 29.970/34.401/39.982/4.444 ms