Receiving duplicates is quite uncommon. Usually, they signify an IP address conflict (two nodes sharing the same IP address), inappropriate retransmissions at the link layer (even possible loops), perhaps issues with the active/backup configuration of these servers.
The first thing I would try is to use the arping UNIX utility to find out if two or more stations in the network share the same IP. The arping sends out ARP Request packets and awaits responses. If two or more different MAC addresses are displayed in the output then it means that more than one station is considering the pinged IP address as its own.
If only one station responds then I would personally follow the path from the pinging server towards the 192.168.2.20 and check each cable and each device on the path for any abnormal behavior or configuration. Duplicate packets do not have a single reason for occurence so we are looking for anything that could cause this behavior. Look for spanning tree issues, flapping ports or duplicate MAC addresses being reported, EtherChannel misconfigurations, ... it is hard to enumerate, considering the plethora of diverse technologies you may be using. You will need to perform quite a thorough check.