When I lived in Lakewood I had one of the frum internet providers and I know they assigned all their users the same ip address, including my parents in NY had the same ip I had in NJ. Other internet providers do the same, even though it isn’t the most common method. So, yes, it is quite possible and very reasonable that two or more users share an ip. Even if they live in different cities.
So one guy might have been in Melbourne and another in another Australian city with a earlier or later Zman Shabbos. Hence the 25 hour difference.
Although, we still don’t know the *exact* alleged difference in hours and minutes between the Friday and Sat. Night post.