Is a pilgrim in the state of Ihram permitted to wear sandals with two straps, and has there been a prohibition reported regarding what a pilgrim in Ihram may wear on his feet?

The Sunnah for a male is to enter into ihram while wearing sandals, due to the Prophet's (peace and blessings be upon him) saying: "Let one of you enter into ihram in an izar (waist wrap), a rida' (upper garment), and sandals." This is preferable for protecting the feet. However, there is no harm if he does not enter into ihram while wearing them. Sandals are what is worn on the foot to protect it, and the straps are not a consideration.