FileChooser on_selection fires multiple times

main.py

'''
Example of an Android filechooser.
'''

from __future__ import unicode_literals
from textwrap import dedent

from plyer import filechooser

from kivy.app import App
from kivy.lang import Builder
from kivy.properties import ListProperty, NumericProperty
from kivy.uix.button import Button


class FileChoose(Button):
    '''
    Button that triggers 'filechooser.open_file()' and processes
    the data response from filechooser Activity.
    '''

    selection = ListProperty([])
    count = NumericProperty(0)

    def choose(self):
        '''
        Call plyer filechooser API to run a filechooser Activity.
        '''
        filechooser.open_file(on_selection=self.handle_selection)

    def handle_selection(self, selection):
        '''
        Callback function for handling the selection response from Activity.
        '''
        self.count = self.count + 1
        self.selection = selection

    def on_selection(self, *a, **k):
        '''
        Update TextInput.text after FileChoose.selection is changed
        via FileChoose.handle_selection.
        '''
        App.get_running_app().root.ids.result.text = str(
            self.selection) + " - " + str(self.count)

class ChooserApp(App):
    '''
    Application class with root built in KV.
    '''

    def build(self):
        return Builder.load_string(dedent('''
            <FileChoose>:

            BoxLayout:

                BoxLayout:
                    orientation: 'vertical'

                    TextInput:
                        id: result
                        text: ''
                        hint_text: 'selected path'

                    FileChoose:
                        size_hint_y: 0.1
                        on_release: self.choose()
                        text: 'Select a file'
        '''))


if __name__ == '__main__':
    ChooserApp().run()