Ping reply DUP! error

hi there..
i'm using ubuntu 6.06 dapper drake
when i ping to my webserver, this is the result :

me@buzz:~$ ping 172.10.30.26
PING 172.10.30.26 (172.10.30.26) 56(84) bytes of data.
64 bytes from 172.10.30.26: icmp_seq=1 ttl=254 time=0.194 ms
64 bytes from 172.10.30.26: icmp_seq=1 ttl=254 time=0.213 ms (DUP!)
64 bytes from 172.10.30.26: icmp_seq=2 ttl=254 time=0.180 ms
64 bytes from 172.10.30.26: icmp_seq=2 ttl=254 time=0.200 ms (DUP!)
64 bytes from 172.10.30.26: icmp_seq=3 ttl=254 time=0.205 ms
64 bytes from 172.10.30.26: icmp_seq=3 ttl=254 time=0.225 ms (DUP!)
64 bytes from 172.10.30.26: icmp_seq=4 ttl=254 time=0.186 ms
64 bytes from 172.10.30.26: icmp_seq=4 ttl=254 time=0.208 ms (DUP!)

i try ping using different device (switch) & the result:

me@buzz:~$ ping 172.10.60.254
PING 172.10.60.254 (172.10.60.254) 56(84) bytes of data.
64 bytes from 172.10.60.254: icmp_seq=1 ttl=63 time=2.40 ms
64 bytes from 172.10.60.254: icmp_seq=1 ttl=63 time=2.44 ms (DUP!)
64 bytes from 172.10.60.254: icmp_seq=2 ttl=63 time=2.88 ms
64 bytes from 172.10.60.254: icmp_seq=2 ttl=63 time=2.90 ms (DUP!)
64 bytes from 172.10.60.254: icmp_seq=3 ttl=63 time=2.05 ms
64 bytes from 172.10.60.254: icmp_seq=3 ttl=63 time=2.08 ms (DUP!)

then i try ping from different vlan with the same device
the result:

me@buzz:~$ ping 172.10.30.26
PING 172.10.30.26 (172.10.30.26) 56(84) bytes of data.
64 bytes from 172.10.30.26: icmp_seq=1 ttl=254 time=0.194 ms
64 bytes from 172.10.30.26: icmp_seq=1 ttl=254 time=0.213 ms
64 bytes from 172.10.30.26: icmp_seq=2 ttl=254 time=0.180 ms
64 bytes from 172.10.30.26: icmp_seq=2 ttl=254 time=0.200 ms
64 bytes from 172.10.30.26: icmp_seq=3 ttl=254 time=0.205 ms
64 bytes from 172.10.30.26: icmp_seq=3 ttl=254 time=0.225 ms
64 bytes from 172.10.30.26: icmp_seq=4 ttl=254 time=0.186 ms
64 bytes from 172.10.30.26: icmp_seq=4 ttl=254 time=0.208 ms

Question

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1- Using man ping, it said that there was duplicate and damaged packets. How to trace this duplicate and damaged packets?

2-Is it possible that the problem come from faulty device such as router/switch?

3-If i'm using WinXP, the ping result is normal. Why ping result different using Linux & WinXP?

I have normally seen dupe errors with pings when there is a physical problem with the switchport. It could possibly be the network cable as well. One reason you could be seeing the problem with Ubuntu, and not with Windows XP is the byte size of XP's ping packets. Ubuntu has a longer packet (twice as long) so perhaps the errors are occurring at a higher bit count than the default ping byte size for Windows.

To test that use the -l switch to increase the packet size in Windows XP Ping.

[code:1]ping 10.10.10.10 -l 1400[/code:1]

Will send a 1400byte ping to 10.10.10.10

Cheers