47 Grk “answered and said to them.” The expression, redundant in English, has been simplified to “replied.”
48 Grk “Jesus I know about.” Here Ἰησοῦν (Iēsoun) is in emphatic position in Greek, but placing the object first is not normal in contemporary English style.
49 ἐπίσταμαι 2 has “know, be acquainted with τινά … τὸν Παῦλον Ac 19:15.” Here the translation “be acquainted with” was used to differentiate from the previous phrase which has γινώσκω (ginōskō).
50 But who are you? This account shows how the power of Paul was so distinct that parallel claims to access that power were denied. In fact, such manipulation, by those who did not know Jesus, was judged (v. 16). The indirect way in which the exorcists made the appeal shows their distance from Jesus.

In other versions

But the evil spirit answered them, “Jesus I know, and Paul I recognize, but who are you?”

One day the evil spirit answered them, “Jesus I know, and Paul I know about, but who are you?”

The evil spirit answered them, “I know Jesus, and I recognize Paul—but who are you?”

But one time when they tried it, the evil spirit replied, “I know Jesus, and I know Paul, but who are you?”

But the evil spirit answered and said to them, “Jesus I know, and Paul I am acquainted with, but who are you?”

And the evil spirit answered and said, Jesus I know, and Paul I know; but who are ye?

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