Database Software

Hi,
I have handle 10g database ,in 10g database two instance x1,x2 in x1 when i fired
show parameter service_name
NAME TYPE VALUE
------------------------ ----------- ------------------------------
service_names string x1, x, SYS$SYS.KUPC$S_1_
20070118101217.x
also fired these command in instance x2

NAME TYPE VALUE
------------------------ ----------- ------------------------------
service_names string x2, x
in instance x1 why VALUE is sys$sys.kupc$s_1_20070118101217.x
but i am only alter system set="x1","x1" scope=memory sid="x1"
but why should these occured?
anybody explain me?