Revision history: Dupe system

A dupe system gives duplicate copies of a character mechanical value instead of letting them be dead pulls. In Genshin Impact duplicates become Constellations, in Honkai: Star Rail Eidolons, in many Japanese games "limit breaks": each additional copy, usually up to six, unlocks a stat boost or ability upgrade. [1]

The design has a quiet economic function: it multiplies the ceiling on what one player can spend on one banner. Fully upgrading a character in a 90-pity, 50/50 game means securing up to seven copies, a worst case of 1,260 pulls, versus 180 for a single copy. Dupe systems are therefore the main lever behind whale-tier spending, and balance debates often center on how much power is locked behind them.

Design variation is wide. Support-card games like Umamusume: Pretty Derby make limit breaks nearly mandatory for competitiveness, because card effects scale steeply with copies. Games like Blue Archive soften the pressure by letting spark exchanges and farmable shards substitute for pulled duplicates. Where a game sits on that spectrum is one of the better predictors of its long-term cost profile, independent of its headline rates.