With the command /rps 2 server you unset the variable %server2 and var %server3 took %server2's place, and etc... Example
We Have Variables: %server1 asd %server2 asd2 %server3 asd3 %server4 asd4
rps 2 server (%server2)
Now We have variables:
%server1 asd %server2 asd3 %server3 asd4