Last modified date

This is wonderful plugin. I was able to show only the last modified date now in my posts. I have one query. I checked google rich snippet and it shows both datepublshed and datemodified. All along google has been taking only date published. Now which one google would take it? Here is the google rich snippets screenshot.

https://search.google.com/test/rich-results?utm_campaign=sdtt&utm_medium=message&id=L3MGOvQNAu6WmeiWuOR4qw
If still google shows only datepublished, what is the way to show datemodified?

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