When you write QML application using MarbleDeclarativeWidget and declare several (at least two) DataLayers with different list models, Marble shows only the last dataLayer and doesn't show other layers. 

Reproducible: Always

Steps to Reproduce:
1. Create QML application with 2 dataLayers (see code examples below)
2. Run the application and see only the second layer at the map.
#----------------- QML files---------------------------------------------------------
//#### Layer.qml #######################################
import QtQuick 1.1
import org.kde.edu.marble 0.11

MarbleWidget {
    id: widget
    width: 800;
    height: 600
    dataLayers: [

        DataLayer{
            id: la1
            // The model defines the data that will appear. The lon and lat
            // property of its items define their position
            // See SevenWondersOfTheAncientWorld.qml for details
            model: Model1 {}
            delegate: Rectangle {
                width: 100;
                height: 20;
                border.color: "darkgray"; border.width: 2
                radius: 4; smooth: true
                Column {
                    id: column; x: 4; y: 4; spacing: 4
                    Text {
                        id: label
                        // "name" is a property defined by items in the model
                        text: "Delegate#2"
                        width: 92
                        wrapMode: Text.Wrap
                        font.bold: true
                    }
                }
            }
        }
       ,

    DataLayer{
        id: la2
        model: Model2{}
        delegate: Rectangle {
            width: 100;
            height: 20;
            color: "blue"
            Text {
                anchors.centerIn: parent
                font.bold: true
                text: "Delegate#1"
            }
        }
    }
   ]
}
//########### Model1.qml #########################
import QtQuick 1.1

ListModel {
    ListElement{
        lon: 44.4275; lat: 32.5355
    }
    ListElement{
        lon: 28.227778; lat: 36.451111
    }
    ListElement{
        lon: 31.134358; lat: 29.979175
    }
}
############## Model2.qml ####################
import QtQuick 1.1

ListModel {

    ListElement{
        lon: 70.424056; lat: 47.037944
    }
    ListElement{
        lon: 75.363889; lat: 47.949722
    }
    ListElement{
        lon: 80.63; lat: 47.637861
    }
}
//######### End ###########
Actual Results:  
You see only the last dataLayer on the map.

Expected Results:  
You should see all dataLayers on the map.

I have spend some time to investigate this bug. and make following conclusions:
    1) function void LayerManager::Private::addPlugins() looks in the variable m_renderPlugins, and if it is not contain element with current name add this element to m_renderPlugins.
 In my test application addPlugins() adds the first plugin with dataLayer - "DeclarativeDataPlugin_1" 
when addPlugins() is called to add the second plugin with dataLayer - "DeclarativeDataPlugin_2", but the m_renderPlugins contains the element with name "DeclarativeDataPlugin_2" (instead of  "DeclarativeDataPlugin_1"). "DeclarativeDataPlugin_2 in m_renderPlugins has the same address with  "DeclarativeDataPlugin_1" . Something change this elent and I don't understand what is that.
--- So, we need to go deeper---------
   2)  We should look at function "Marble::RenderPlugin *DeclarativeDataPlugin::newInstance(const Marble::MarbleModel *marbleModel) const"
if you add qDebug to the start and to the end of this function 
( qDebug() << "Instance NameID Before" << d->m_nameId;
qDebug() << "Instance After NameID" << instance->nameId();)
you see, that the name ID is different.  I have add this "dog-nail" 

Marble::RenderPlugin *DeclarativeDataPlugin::newInstance(const Marble::MarbleModel *marbleModel) const
{
    QString name_Id_tmp = nameId();
      .
      .
    d->m_modelInstances << dataModel;
     instance->setNameId(name_Id_tmp);
    qDebug() << "Instance After NameID" << instance->nameId();
    return instance;
}

and the becomes not reproducible (I see all dataLayers on the map).
I can't find the reason, why nameId is changed in this function, but this fix works. 
Dear Marble Developers, could you tell me your mine about this bug. Where I should look to find the real reason of this bug?