A player calls a discarded tile while another player simultaneously racks the tile they picked; the player who called the discarded tile is entitled to it.
Simultaneous Call for a Discard with Both for Mah Jongg (Article ID 92)
When two players simultaneously call the same tile for mah jongg, the player next in turn gets the tile.
Simultaneous Call for a Discard to Expose (Article ID 93)
When two players call the same tile, the player next in turn gets the tile.
Simultaneous Call for a Misnamed Discard (Article ID 94)
A tile is discarded and misnamed, and two players call for mah jongg
Simultaneous Call One for Mah Jongg and One for an Exposure (Article ID 95)
When two players verbalize a call for the same discard, the player next has the first right of refusal unless the other player has also exposed tiles.