In the FAQ for Isotropic's online Dominion game, the creator states:
No, you really can reveal a reaction card like Moat or Secret Chamber multiple times. They are designed to be idempotent so there's no point in doing so, but allowing this avoids strange corner cases having to do with Secret Chamber drawing other reaction cards.
What, exactly, are these corner cases? Can you reveal a reaction card drawn from Secret Chamber, or is there some other strange case drawing a reaction card with Secret Chamber causes?