Duplicate IDs cause failure in W3C's HTML compliance Test

I was validating my web site with the official W3C’s Markup Validation Service (https://validator.w3.org/) and I noticed that a couple of errors are generated by your plugin.
Errors derive from the fact that the plugin duplicates the IDs “flags”, “sortable” and the id generated by the default language.
IDs should be unique (https://www.w3schools.com/tags/att_global_id.asp): if you need to select groups of elements, use a particular class or define a custom attribute “data- *” (https://www.w3schools.com/tags/att_global_data.asp)