Some, of course, interpret the material in Revelation 11 in a literal matter. The two witnesses are said to be two individuals who will create real plagues. A symbolic interpretation avoids these problems of interpretation. The temple, for example, could be the church and not a physical building. Indeed, that is the New Testament meaning of the temple.
Revelation pictures the church as a martyr church.
That the two witnesses are called lampstands indicates how Revelation understands their role. Perhaps that is the sense in which we should understand the two witnesses. It seems possible, then, to explain the two witnesses as symbols of the witnessing church. Certainly, that was the role of the church in the days of the apostles.