Parashas Acharei Mos · Passuk 18:22
Chabad.org — English translation + Rashi
Torah Temima points to Sanhedrin 54b.
English: One who both acts and is acted upon with a male incurs, according to R. Akiva, only a single liability — the two readings are one warning.
Single liability for dual role
Under R. Akiva the dual reading yields one azharah, hence one count even when both roles are performed.