can someone help me with these before/after sliders?

hi guys

I am trying to add more than one before/after slider in my product page (https://www.federicoperale.com/lightroom-presets) using the code I found in this page (https://www.sparkplugin.com/blog/before-after-image-slider-in-squarespace)

there seems to be an issue when having more than one. the second one never works, and displays only one photo instead of two. the slider doesn't move. 

any idea what I am doing wrong?

many thanks

Fed