replaying the magento pcap capture fails for more that one session in quick successio

i am trying to replay a pcap capture using tcp socket, which is just a login and logout with a different username and password to a magento server. the server response was 200 ok ,

but when i start the playing the pcap from 4 different ssh sessions for 4 different user in quick succession ie. less than 1 sec difference, the first login logout session passes ie i get 200 ok from the server , but for the other two sessions i get 302 response .

if i play the pcap at a time difference of 5 sec , all the 4 sessions passes ,

my understanding on this issue is ,for the 1st user's POST message the server provides new cookies but for the other 3 users POST message the server did not provide new cookies.

i have a pcap capture of all the 4 users, in which the packet number 153,156,159 and 162 explains the scenario.