ExtJs 3.4 display error textfield in xtype: 'textfield' (MODx)

I've got a panel which button shows this window:

   MyClass.window.Test = function (config) {
    config = config || {};
    Ext.applyIf(config, {
        title: 'Test',
        width: '1000',
        autoHeight: true,
        fields: [
            {
                xtype: 'panel',
                items: [{
                        layout: 'form',
                        items: [
                            {
                                xtype: 'textfield',
                                name: 'testfield',
                                fieldLabel: 'Test Label Textfield',
                                id: 'testfield',
                                emptyText: 'text',
                                allowBlank: true,
                                anchor:'95%'
                            }
                        ]
                    },
                ]}
        ],
        url: MyClass.config.connector_url,
        action: 'mgr/myext/create',
    });
    MyClass.window.Test.superclass.constructor.call(this, config);
};
Ext.extend(MyClass.window.Test, MODx.Window);
Ext.reg('test-window', MyClass.window.Test, MODx.Window);

the button itself is like this

{
xtype: 'button',
text: 'TEST',
cls: 'primary-button',
                handler:   function () {
                    MODx.load({
                        xtype: 'test-window',
                        listeners: {
                            success: {
                                fn: function () {
                                    this.refresh();
                                }, scope: this 
                            }
                        }
                    }).show();
                }
}

Problem. When I click on the button for the first time, the form displays correctlly. When I click for the second time, textfield disappears and fieldLabel duplicates 4 times (1 click normall 2 click and more - crash). If I replace textfield with any other xtype - everything works well. If remove id it works well(!!!). But I need id for Ext.getCmp. I don't understand why everything is good at the first time, but when I click again it doesn't show correctly. I couldn't find the similar problem anywhere, and was frustrated. Any manipulations with fieldlabel, layuot properties don't help. Where can be the problem? In working version I have around 40 textfield.

The window is not destroyed on close by default, so you have two elements with the same id creating the window again.

this.ident = config.ident || 'mywindow' + Ext.id();

at the start of the window code after

config = config || {};

and later on using

id: 'textfield' + this.ident

will help to bypass that issue.