Istikhaarah is a supplication (Dua) in which the Muslim asks his Lord, may He be Glorified and Exalted, to choose for him the better of two things. According to Islamic teachings, the matter of supplication is broad in scope, and it is permissible for the Muslim to ask Allah, Ta’ala in his supplication for all that he needs. The Prophet (Sallallahu Alayhi Wasallam) used to like concise supplications, which are those that include many meanings in a few words. There does not seem to be any reason to disallow mentioning more than one matter in Istikhaarah, after praying two Rak‘ahs, and by doing so he will have done what is required of praying two Rak‘ahs, then offering the Dua of Istikhaarah regarding his need after that. However, it is better to have one prayer and supplication for each matter.