Can two sisters be married in one ceremony on the same day?

Yes; each akad stands on its own, so two marriages can be conducted one after the other in the same ceremony. The same wali can marry off both his daughters, and the same two witnesses can witness both akads. What matters is that each akad has its own ijab and qabul with the correct names and mahr. Each couple also needs its own permission to marry and separate registration. Let the religious office know early so the marriage officiant can plan the timing. A joint ceremony can also save on walimah costs. See Conditions of the akad.