[R1 Errata] No. The curse deck should be split into two equal decks of 10 cards each (Rev 2 has symbols on the cards denoting this).

One deck is exclusively for putting curse cards into the player's attack modifier decks, and the other is exclusively for putting curse cards into the monster's attack modifier deck. So no single attack modifier deck can ever have more than 10 curse cards in it. When a curse card is removed from a player’s attack modifier deck, it is returned to the player curse card deck, and a curse card removed from the monster attack modifier deck is returned to the monster curse card deck. If curses are distributed at the beginning of a scenario, distribute them as evenly as possible to all those affected, with players deciding cases of ambiguity.