If you go into the my disney experience app and click on that fastpass you'll see that each of your people has two of the anytime fastpasses assigned to them. Viewing it in a web browser will make it look like it's one fastpass for ten people.
It will disappear once you tap (or rather go down to saying it is for five guests after the first ride). The replacement anytime fastpass will tell you what it is good for, which should be for the ride you originally had or any other ride in that park that isn't more popular than it. If you find this not to be the case I'm sure Disney would fix it for you. Though their phone lines may have quite the wait, so I'd do it another day.
If you try to use normal fastpasses before the anytime fastpass, I would use the normal fastpass during the hour period it is for (not the few minutes early or late that they typically allow).
Also, I'd suggest trying to add additional fastpasses for that day, even though that isn't how that should work. I'm now up to three replacement fastpasses and three normal ones.
