create 2 custom columns in page edit in Admin panel

functions attached to manage_pages_custom_column get fired for every custom column, you have to check the name of the column within the function to only output data for that specific column:

add_action( 'manage_pages_custom_column', 'AddColumnValue', 10, 2 );

function AddColumnValue( $column_name, $post_id ) {
    if( 'thumbnail' == $column_name ):
        echo 'Header Image data here';
    elseif( 'cssColor' == $column_name ):
        //code goes here for second column
    endif;
}