App resources get loaded twice

Summary

A Vendor encountered an apparent but that makes their plugin resources be loaded and executed twice in some Confluence versions >= 7.16.0 and < 8.0.0, and if other certain macros are also on the page.

Steps to reproduce

• Start a clean Confluence 7.16.0 <= version < 8.0.0
• Install Multivote & Enterprise Survey for Confluence: https://marketplace.atlassian.com/apps/1210786/multivote-enterprise-survey-for-confluence?hosting=datacenter&tab=overview
• Install Refined Toolkit for Confluence: https://marketplace.atlassian.com/apps/1211136/refined-toolkit-for-confluence?hosting=datacenter&tab=overview 
• Create a new page

• • Add a "Multivote macro"
  • Add any UI macro from Refined (e.g., "UI Button")
• Save the page

Expected result: everything works as expected, as if only one of the macros is present on the page
Actual result: Multivote resources are loaded and executed twice and all REST calls to MV are executed twice

The vendor elaborates that as this behaviour is not seen in all Confluence versions, there may be a bug present regarding web resource loading in combination with Webpack and the Atlassian webresource-webpack-plugin that both apps use.