Ivysaur and his skills [Minor issue]

Hi everyone !

I just begin the game (3 pkmn lvl 20 yay), and I chose bulbasaur as first. After some time playing, i saw that the pokedex shows the skills a pokemon can learn, and at which lvl. AND, my bulbasaur should learn poison and sleep powder, both lvl 13. In fact, he only learned sleep powder.

Then, some time later, (lvl 20 indeed), ivysaur should learn razor leaf. It ask me if I wanted him to learn razor leaf. So I said yes. Then in combat it was not razor leaf but poison powder. So i'm left with vine whip as only damage skill ;_;

Another fellow ivysaur trainer got razor leaf, but he never heard about poison powder.

Is there any problem with multiple skills learned at a same lvl ?