Cannot find it. :(
The problem is only when i cast both of my summon and next battle occurs quickly, dunno exactly what i could have messed up. :(
If i summon A, then then i kill the monster, with summon still on CD, i can use it next battle, immediately.
If i summon B, then then i kill the monster, with summon still on CD, i can use it next battle, immediately.
If i summon A and then B, then i kill the monster, with both still on CD, i can use A next battle, but not B. In this case, if i use A, then it is unavailable next battle, instead B become again usable.... If i don't use summons for a battle, both spells are available again...
Same if i invert A with B....
I am getting mad. :D