Duplicated buttons in top panel

[DartVerder]

Environment:
GrapesJs add-on version: 0.5.3
CUBA Platform version: 7.2.13
CUBA Studio plugin version: 15.3-202

Descriptions of the bug:

1. Add grapesJS HTML Editor addon from the marketplace
2. Create the screen with HTML Editor

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<window xmlns="http://schemas.haulmont.com/cuba/screen/window.xsd"
        caption="msg://newScreen.caption"
        messagesPack="com.company.untitled8.web.screens"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://schemas.haulmont.com/grapesjs/ui-component.xsd ">
    <layout>
        <xsi:grapesJsWebpageHtmlEditor id="htmlEditor">
            <xsi:disabledBlocks>
                map,tabs
            </xsi:disabledBlocks>
        </xsi:grapesJsWebpageHtmlEditor>
    </layout>
</window>

3. Run application
4. Open created screen

ER: each button on the top panel is unique
AR: some buttons on the top panel are duplicated