What produces double tooth?

Developmental proble: it is called supernumerary tooth where when teeth are developing in a bud stage gets fused. Good luck

Genetics: Fusion is two adjacent teeth that have merged. Gemination. is a single tooth that partially divides into a double tooth. Supernumerary teeth are extra teeth. A m esiodens is an extra tooth in the midline. Dens in denté is a miniature extra tooth forming inside a normal tooth. All are of genetic origin and begin forming before birth. See your Dentist for evaluation and, if necessary, treatment.