i did it a while back on my main, read several guides so i knew my FP to take around dalaran, some of the book spawns can be seen through windows
, took a few minutes to do a full run of the spawn points. I would always try and be in dalaran before a server restart/reset, and would log back in as soon as the server went back up, took a few attempts but after a while i was only 1 or 2 books away from achieve. Then i changed tactics, i would just check the last couple of spots every time i was in dalaran on that toon, and sure enough one weekend i got lucky and got both at random on the same day. I always read the fake books to despawn them, and would make a mental note to recheck that spot 3 hours later, of ten i would camp for that 1 hour as the books do have a 3-4 hour respawn timer. I was on a medium pop server and got the pet towards the end of cata, would have been sooner but i often worked shift work so could not do every tuesday reset/restart of servers, a high pop server can work to your advantage as if you get to know other book hunters, they might be inclined to let you know if a book spawns, other pet collectors are your best resource i always find.