How is an adopted child called up to the Torah for an Aliya? With which father’s name?

If he knows his biological father, it's better that he be called with his name, especially if one of the fathers is a Kohen or Levi, where it will otherwise lead to confusion (and any way, everyone will know). On the other hand if he (or his adopting father) is embarrassed not to use the adopting father's name, he can rely on the lenient opinion of R. Sh. Z. Auerbach who allows to do so, especially if both fathers are regular Yisraels.