I'll explain what I mean by the casino senses threat, there are people in time past who engaged in some illegal sport betting activity by getting an inside information from a match, now this match can be fixed or manipulated by a single person for instance, betting on payer A not to score in a match, and each time player A has a scoring opportunity, he deliberately misses.
However those who got the inside information would likely place this same bet on different sportsbook to avoid suspicion.
Someone who finds such insider information won't make normal bets in the first place, and a casino will sense something suspicious is going on if a sports bettor who doesn't make bets larger than $100 suddenly makes a bet worth a few thousand dollars, which does make it suspicious. However, if a sports bettor makes the same amount of bet, the sportsbook won't suspect anything, and if they later find out that the game was rigged, they mostly reverse the rewards and return the bet amount, as far as I know, sportsbooks and casinos deal with such things this way.
What OP has asked is similar to arbitrage betting, but a bit different, because when you are doing arbitrage betting, you don't use different platforms and place your bet on the same side, but you basically use all possible outcomes to get a small amount of profits that can be found in between the odds. It basically doesn't make any sense to me for one to use different platforms to make the same bet with the same selection, because that isn't going to get them any yield, imagine if they lose the bet, they lose on both platforms.
