You did nothing wrong, the website just is poorly made. This is a special type of HitCircle that needs a specific value on HitCircleOverlap in the skin.ini, but the website doesn't set it automatically.
miguree wrote:for some reason, when i was trying out my skin some of the hit circles ended up like this, as if they were doubled
but when i use a different skin or the default skin it looks perfectly fine (these are the same parts of the beatmap)
did i do something wrong??