Is Bigg Boss trying to write a script where they are trying to start a rivalry between Rubina and Pavitra like Gauhar-Tanisha, Shilpa-Hina or Bani-Lopa?
As Rubina is a Colors bahu, she may very well be the fixed winner this season, and they might have thought of making Jasmine the main rival for her. But as she's too childish, she can at best be a second runner up like Shehnaaz.
So they are going with Pavitra, to make her the second runner up, who too is a popular face on television, and other main competitor was supposed to be Eijaz Khan who turned out to be a phuski bomb.
So they are trying to create a rivalry by giving them tasks were they have to compete against each other. If my intuition is true, Bigg Boss would keep on giving them tasks where they have to directly compete against each other, to create tensions between them.