Official rule text
8.3 STEP 2—SECOND AGENDA: Players repeat the “First if no outcome receives any votes, the speaker decides which of Agenda” step of this phase for a second agenda. the tied outcomes to resolve.
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Source: Twilight Imperium: Fourth Edition - Living Rules Reference: Prophecy of Kings
Expansion: Prophecy of Kings
Version: 2.0
Reference: Rule 8.3