Re: "in #JSON-LD the keys in objects must be unique" -- why?

Can you help us with a few examples of what you are trying to represent? I
am inclined to believe that @list might be your only way to get ordering
without reimplementing it yourself!

Also, here's the ECMAScript discussion about duplicate keys:

https://esdiscuss.org/topic/json-duplicate-keys

The minutes at the end are actually quite informative about how things like
this happen and the choices such committees have to make.