Existential 'there' works as a dummy subject. And, 'there' is also an adverb of place.
So, in a situation when I need to use them together it is considered correct or needs rewording to sound natural.
Ex- 1.There was a cat there. (Here listener is expected to know the place where the cat was so the speaker choose to replace it with 'there' and speaker wants to emphasise the cat's existence too).
Or, just writing 'A cat was there' will work?