Duplicated photos

Website using the plugin: violinbiscuit.com
WordPress Version : 4.6.1
Instagram Slider Version : 1.3.3
Theme Name : Shapely
My Problem : I have quite a huge problem with this plugin – when the widget is added to the site, it shows duplicated photos – eg. when I want 10 photos to be visible, it shows 20. Is it a problem with new WordPress version, is it something with the widget or maybe my site?
Please, let me know. Thanks in advance.