Some peroxide based toothpastes are divided because the peroxide would bleach out the colored part if they were to contact. People like color in their toothpaste. If it weren't for that, they would just use white. So yes, it is a gimmick. I used to work for sonicare which at the time was developing toothpastes and mouthwashes. I can tell you stuff you don't even want to know, so I won't.