Zone, not a photocopy
A double bottom is two lows in the same price zone, separated by a rally. Students arrive wanting the second low to print the same number as the first. Daily charts of USD/KRW and the KOSPI almost never oblige. We circle a zone. If the second low lands in that zone and the rally between them is obvious, the sketch can continue.
If the second low is far through the zone, the name changes. It may be a continuation of the decline, or a different pattern entirely. Keeping the words double bottom because you already wrote them is the mistake the single-chart sitting is built to catch.
The middle peak is the trigger line
The peak between the two lows is the line we actually wait on. A close above that peak is the confirmation we mark in class. The second low, by itself, is only the second low. I have watched careful people buy the second touch because the shape felt familiar, then sit through a third low that made the original name nonsense.
Draw the middle peak as a horizontal line across the page. If you cannot see it without squinting, you do not have the pattern yet. Bring that sheet to a sitting if it is your chart. Bring your patience if it is ours, on evening two of the circle.