Please fix or remove this system. It's complete garbage. I have absolutely no clue why you thought limiting it to 1 discovery per animal was a good idea. ABSOLUTELY TEDIOUS! I'm wandering around killing literally everything, and all I get is another fucking quick dodge. Here's a simple solution:
You can only get each discovery once. And then it NEVER APPEARS AGAIN.
I get the feeling you've never tried to get them all. Let alone more than once.