26 Aymnius of Ausuaga said: "We have received one baptism, which same also we administer; but he who says that authority is given to heretics also to baptize, the same makes two baptisms."
27. To him we answer: Why does not he also make two baptisms who maintains that the unrighteous also can baptize? For although the righteous and unrighteous are in themselves opposed to one another, yet the baptism which the righteous give, such as was Paul, or such as was also Cyprian, is not contrary to the baptism which those unrighteous men were wont to give who hated Paul, whom Cyprian understands to have been not heretics, but bad Catholics; and although the moderation which was found in Cyprian, and the covetousness which was found in his colleagues, are in themselves opposed to one another, yet the baptism which Cyprian used to give was not contrary to the baptism which his colleagues who opposed him used to give, but one and the same with it, because in both cases it is He that baptizes of whom it is said, "The same is He which baptizes."
Source: On Baptism, Against the Donatists (New Advent)