for( var i = 0; i < FlexView1.RowCount; i++ ){
    var r = FlexView1.GetRow( i );
    if( r.FlexText1.Value == tmpdata ){
        r.FlexLabel1.FgColor = $RED;
            :
            :
    }
}

var row2 = FlexView1.GetRow( 0 );                     <--(1)
String s;
while( !row2.end ) {
    s = row2.FlexText1.value;
    for( var i = 0; i < FlexView1.RowCount; i++ ) {
        var row = FlexView1.GetRow( i );              <--(2)
        if ( s == row.FlexText1.value ){              <--(3)
            /*エラー処理*/
        }
    }
    row2.moveNext();
}

var row2 = FlexView1.GetRow( 0 );
var s;
while( row2.position < FlexView1.RowCount - 1 ) {
    s = row2.FlexText1.value;
    var row = FlexView1.GetRow( row2.position + 1 );
    while( !row.end ) {
        if ( s == row.FlexText1.value ) {
            /*エラー処理*/
        }
        row.MoveNext();
    }
    row2.MoveNext();
}