in the duolingo course they teach that when you have a demonstrative (ez/az) and a postposition you have to put the postposition twice, so for example "in front of this house" is "ez előtt a ház előtt"
but in the comments I've seen many natives claiming that we don't actually speak like that, we would rather say "e ház előtt" (and this is usually also accepted by duo)
also I've seen on some sentences that it's ezen instead of ez, for example here they accept "ezen lámpa alatt" instead of "e lámpa alatt"
and on some it's all 3 that are accepted, for example here they take both "ezen folyó fölött" and "e folyó fölött"
so what gives? are they all correct and it's just a matter of preference?