Same event, same bet? Usually not quite.
Two contracts can share a headline and still pay out differently. Three real cases:
1. Cardi B at the Super Bowl (February 2026)
Both venues listed whether Cardi B would perform at halftime. She appeared in another artist's set. Polymarket resolved YES. Kalshi ruled the question unresolvable and settled at the last traded price — about 26¢. Same facts, opposite economics, because the two rulebooks define "perform" differently.
2. CPI when the data is late
Polymarket's CPI contracts publish exactly what happens if the Bureau of Labor Statistics delays a release (fall back to the previous month within a window). Kalshi's matching contracts publish no such branch. Most months this never matters. In a delay, the two would settle by different rules.
3. Fed decisions and rounding
Polymarket US's Fed-decision buckets publish a rounding rule for moves that don't land on a listed size; Kalshi's do not. An unusual move — an intermeeting cut, an odd increment — is where those texts diverge.
How the verdict on each page is reached
A deterministic rule comparison extracts the economic terms from each venue's published text — subject, threshold, direction, settlement source, revision and cancellation policy — and compares them field by field. A pair is called the same bet only when every term matches and both venues' settlement terms are complete. Anything less is listed with the specific published differences. No model guesses; a lexical match on titles is never enough.