Unable to change sessions parameter

 My sessions parameter is defaulting to the value of processes * 1.1 + 5, regardless of the spfile setting.  the value is correct in v$spparameter, but incorrect in v$parameter.

From create pfile from spfile:
SID1.sessions=600
SID2.sessions=600
*.sessions=500

SQL>  select name||'  '||value from v$parameter where name in ('processes','sessions') ;

NAME||''||VALUE
--------------------------------------------------------------------------------
processes  650
sessions  720

SQL> select name||'  '||value from v$spparameter where name in ('processes','sessions') and sid='SID1' ;

NAME||''||VALUE
--------------------------------------------------------------------------------
processes  650
sessions  600