Marie T. it looks like you are trying to populate a slider with CMS items and using Finsweet CMS Slider, is that correct?
If so, and for some reason you have multiple instances on the same page, you鈥檒l have to do it a little differently otherwise yes, they could break each other.
At the bottom of the documentation there is a section about multiple instances.
additionally, Finsweet has an self-support tool which can help point you in the direction of why your homepage slider stopped working.
https://finsweet.com/attributes/support