You can get more than 1 trove in the isle. After you open 1 chest, quickly rush to other spots and you can open a second or even a third within 3 minutes of opening the first.
This is great on dead realms. A way to optimize the ammount of chests you can get each week, I personally do this:
1. I scout the entire area/each spawn to find out where all chests are up.
2. Once I marked all locations on my map, I theorize which route would get me to each chest the fastest.
3. Open a chest and rush from one chest to another
4. Open them all 1 by 1.
Despite you being able to open multiple chests, I personally only obtained one key for the scenario. So this is mostly for the gold/ chests with a charm of fortune.