I am afraid it's not possible. But you are lucky :D !
Today it's the first birthday of my son.
I made a script that do what you want. Hope this will help you or anyone else.
Have a look to this :

The script is under pull request state, but you can download it on my fork
or get it from this code :
from qgis.core import *
from qgis.gui import *
from qgis.utils import *
from PyQt4.QtCore import QVariant
##Duplicate Fied=name
##input_layer=vector
##field_to_duplicate=field input_layer
##fieldname_list=string
layer = processing.getObject(input_layer)
pr = layer.dataProvider()
caps = pr.capabilities()
def refreshLayer():
layer.setCacheImage( None )
layer.dataProvider().forceReload()
layer.triggerRepaint()
iface.mapCanvas().refreshAllLayers()
fields = layer.pendingFields()
QVariantDict = {
4 : QVariant.Int,
1 : QVariant.Double,
10 : QVariant.String,
14 : QVariant.Date,
}
listFieldName = str(fieldname_list).split(';')
newFieldIndex = len(fields)
FieldIdx=0
for field in fields:
if field.name() == field_to_duplicate:
FieldIdx = fields.indexFromName(field.name())
field_type = QVariantDict[field.type()]
field_precision = field.precision()
field_length = field.length()
field_widget = layer.editorWidgetV2(FieldIdx)
field_widgetConfig = layer.editorWidgetV2Config(FieldIdx)
progress.setText("{},{},{},{}".format(str(field.name()),str(FieldIdx), str(field_widget), str(field_widgetConfig)))
else:
pass
for f in listFieldName:
if f in fields:
pass
else :
if caps & QgsVectorDataProvider.AddAttributes:
modelProperties= QgsField(f, field_type, str(field_length), int(field_precision), QVariant.String )
res = pr.addAttributes([modelProperties])
layer.updateFields()
layer.setEditorWidgetV2(newFieldIndex , field_widget)
layer.setEditorWidgetV2Config(newFieldIndex , field_widgetConfig)
newField_widget = layer.editorWidgetV2(newFieldIndex)
newField_widgetConfig = layer.editorWidgetV2Config(newFieldIndex)
progress.setText("{},{},{},{}".format(str(f),str(newFieldIndex), str(newField_widget), str(newField_widgetConfig)))
newFieldIndex += 1
refreshLayer()
any improvement will be appreciate.