This tense is called "geniş zamanın hikayesi" which means getting present simple and past simple -r and -di affix together. Some examples: *Eskiden tenis oynardım. *Bayramda büyüklerimizi ziyaret ederdik. Question version: *Eskiden tenis oynar mıydım? *Bayramda büyüklerimizi ziyaret eder miydik? However, in your sentence, that is other form of asking that if the person wants to have a coffee: Bir kahve de siz alır mısınız? Bir kahve de siz alır mıydınız? Although this two sentence almost same, the difference from first sentence is, in the situtation like this: You are giving coffee to one. And then you are saying to other one: - Ahh, would you have a coffee too? (- Ahh, siz de kahve alır mıydınız?) Basically you can use two of them in the same meaning in this case.

Would you also like a coffee وانت كمان كنت عاوز قهوة