It’s too large a topic to discuss fully here, but you are ignoring the field of statistics in general. Multiple data points, when available, are used in statistics and science to substantiate each other, even if they don’t land precisely at the same level. Smarter colleges would know this, and therefore would consider both ACT and SAT scores, if submitted, when evaluating an applicant. Stated differently, a slightly lower SAT score submission (by concordance) can serve to substantiate a higher ACT score when considered together.