Historical Rules · 16 July 2010
Rule 614.5
Official source text from the 16 July 2010 Rules release
A replacement effect doesn't invoke itself repeatedly and gets only one opportunity for each event. Example: A player controls two permanents, each with an ability that reads "If a creature you control would deal damage to a creature or player, it deals double that damage to that creature or player instead." A creature that normally deals 2 damage will deal 8 damage -- not just 4, and not an infinite amount.