I was thinking the EXACT same thing!!!
Tapasya HAD taken Uttaran from Icha not once but twice in the show.
Once on the wedding night - her wedding dress as Uttaran, then later when she was kicked out of Jogi's house and stayed in Basti and her old servant got her some clothes from Bundela house she got Icha's suit or saree (can't remember) which Damini saw later when she came back to Thakur household.
And Meethi and Damini were INSISTING that she doesn't take any used dress. In fact, Meethi didn't even show her ANY of her used dresses. She only showed her brand-new dresses which are NOT Uttaran under any circumstances!!
But as Pushkar said, Nani had to go back to her 'poisoning' self to be able to save Mukta from Meethi who, being a millinaire's naatin and sister too, would 'snatch' everything away from Mukta who's poor now! lol