why there are two TargetEntrys in Query when i use "select count(catcode) from pois group by catcode"?

[sunpeng <bluevaley@xxxxxxxxx>]

I've the table 
CREATE TABLE pois
(
   uid integer not null, 
   name VARCHAR(128),
   catcode VARCHAR(32)  not null, 
   catname VARCHAR(32),
   others VARCHAR(32)
);
after i execute "select count(*) from pois group by catcode";
the log of query.targetList is :
 :targetList (
          {TARGETENTRY 
          :expr 
             {AGGREF 
             :aggfnoid 2803 
             :aggtype 20 
             :args <> 
             :agglevelsup 0 
             :aggstar true 
             :aggdistinct false 
             :location 7
             }
          :resno 1 
          :resname count 
          :ressortgroupref 0 
          :resorigtbl 0 
          :resorigcol 0 
          :resjunk false
          }
          {TARGETENTRY 
          :expr 
             {VAR 
             :varno 1 
             :varattno 3 
             :vartype 1043 
             :vartypmod 36 
             :varlevelsup 0 
             :varnoold 1 
             :varoattno 3 
             :location 35
             }
          :resno 2 
          :resname <> 
          :ressortgroupref 1 
          :resorigtbl 0 
          :resorigcol 0 
          :resjunk true
          }
       )
why there is the second TARGETENTRY? what's the purpose of the second TARGETENTRY?