I’ve been collecting orbs several times in a row and only a copy of the bestiary page always opens. I opened 143 pages and this figure does not change. Is that a bug?
The very first Bestiary hand-in of the day was changed to have an improved chance of giving you a page you don’t already have, but it’s never guaranteed. There are 159 possible pages and which one you get on your first three hand-ins of the day is random. If you already have 143/159 pages collected, this means there are 16 pages left to collect. Therefore each time you get a random page there’s a 143/169 chance it’ll be a duplicate, i.e. 89.937% of a duplicate. As you get closer to 159 collected, the chances of the random page being one of the missing ones becomes slimmer and slimmer.