get only updated data on data change from opcua server

[sudhapc]

I have subscribed to data change event in my opcua client and am able to listen event from opcua server when there is data change like displayname,description,value.
but event is raised multiple times
first am getting old data
secondly am getting updated data

i want to get only the latest data from my opcua server.
what should i do in my server side ? please help