The only reason pine had 2 at a time is because you upgraded to max, so it doesn't count as 1 if its a different level, in easier terms, you upgraded him, which caused his cooldown to start going again so he can summon his new improved one.
Pineberry will be so easy to place if Pineberry is in tower heroes too so much players in tower heroes is already pro and skipping waves (stacks enemies but giving more mana)