I was suspicious of it as soon as she entered the house with that smile but was sure of it as soon as she started speaking. Her voice is different than Aastha's.
Either Aastha's been kidnapped by Payaal (which I hope not, especially if Aastha went there in hopes of finding Payal to reunite her with Swayam) or Aastha is going to pop up out of no-where and be like "gotcha"!