Quick note on the tone question - I didn’t read Lilly’s replies as rude, just brief answers to a question that wasn’t fully clear yet from the outside and a hint that the aspect of links not working for everyone might be unrelated to her component.
On the actual problem: having two sections share the same slug isn’t an issue by itself - they can coexist fine in the sidebar.
This component positions sections via data-section-name in CSS, and that’s the only stable hook exposed in the rendered DOM. There’s no separate ID for a section beyond its slug, so two sections with an identical name can’t be assigned different order values - the component can’t tell them apart, and neither could any other CSS-based approach, since the DOM simply doesn’t expose anything more granular to select on.
So this isn’t a matter of a small improvement, as you suggested with the ID idea - it would require the DOM to expose something Discourse currently doesn’t or a fundamentally different approach.
I am still not entirely sure what your problem is with the reorder component regarding it using slugs. In your example both sections are next to each other - this would work fine with this component. Maybe you can still help to clarify what exactly your problem was with reordering your sections.