Microsoft an Work Account with same E-Mail on IPhone (IOS)

Hi EveryOne!

I have following problem. User activated with his E-Mail an Microsoft account. Now we sync the User to cloud (Azure AD) an want to activate Teams on IPhone with his new Office 365 Working Account. ON windows and Android i can switch between Micrososft and working account, but on Iphone (IOS) i cant. IOS always takes the Micrososft account. Are there any suggestions to solve this problem?