Orphan Black has many impersonations among the sisters, beginning of course with Sarah stepping into Beth's shoes; there's also
- Sarah as Katja, to retrieve the briefcase (s1e2)
- Helena as Beth, at the police station
- Alison as Sarah, for Siobhan (s1e4)
- Sarah as Alison, at the house party (s1e6)
- Helena as Sarah, to meet their host mother (s1e10)
- Sarah as Cosima, at a Dyad reception (s2e1)
- Sarah as Rachel, to get into her apartment (s2e4)
- Sarah as Alison (unintentionally) at rehab (s2e7)
- Rachel as Sarah, to snatch Kira (s2e9)
- Sarah and Alison as Rachel and Sarah, to bluff Ferdinand (s3e1)
- Cosima as Alison (unintentionally) at the election event (s3e7)
- Krystal as Rachel, unwittingly (s3e8–10)
- Helena as Alison, at least four times so far
I don't think anyone has impersonated Helena yet. I omitted simple errors without intent to deceive, as when Vic first met Alison.
Have there been any more instances in which one clone has impersonated another?