How a two-way stake split works
When two books disagree enough, one bet at each can return about the same amount whatever the result. That only holds at those exact prices. Prices move in seconds, books can cancel or limit bets, and rules (overtime, voids) can differ between books, so check both prices and both books' rules before you place anything.
Read more in what a LOCK (arbitrage) is, and why books limit accounts.