As someone else has already pointed out, there are actually many similarities between Purvi and Ovi. I thought it may be interesting to list the parallels and differences between the two characters and their destinies, which seem inextricably intertwined through other characters in the story.
And I also want to say that as much as we critique the CVs for their pathetic repetition, I think they truly deserve compliments for drawing two characters so similar and yet arousing contrary responses in different fan groups. I think it is also clever that even though Teju and Ovi are actual twins, it is Purvi and Ovi whose destinies are linked like Siamese twins. If the tracks were not so repetitious with leaps and all, the writers could perhaps have made a mark for developing a gripping story line with two parallel characters with intertwined destinies, which are very similar in some respects and very different in others.
So, here is my list - you may add to it or take it the way you like. I am not doing this for debate; just to state what I find interesting.
Appearance
Both Purvi and Ovi are very pretty, even though their sense of dressing and the ways of carrying themselves are very different.
Professional life
Both Purvi and Ovi are professional women. One is a successful business person and the other a successful model.
Growing up with a single parent -
Both grew with single parents with different sets of challenges and different implications for their personalities
Purvi - economic challenges and need to develop an overgrown sense of responsibility
Ovi - emotional starvation of mother's love with poor compensation in everyone meeting her demands (a thing that is actually detrimental to a child leading to spoiled brat behavior)
A fierce sense of loyalty
Both Purvi and Ovi have a fierce sense of loyalty to people to whom they got attached in their childhoods
Purvi - loyal to Archana
Ovi - loyal to Arjun
Complex trajectory of destiny
Purvi - orphaned as an infant, raised by a woman and her mother who showered immense love on her, became professional at a young age, was wronged in her first engagement, fell in love with her boss with whom she had fought fiercely, was kept in dark by this man about his earlier agreement to marry someone else who happened to be her sister by relation, was asked to enter a deal for the sake of her mother by that sister, emotionally manipulated her lover to marry the sister, ran away to hide her pregnancy and to protect the marriage she had forced her lover into, survived due to the kindness of a doctor who also married her for protecting her reputation, then emotionally forced him to swap babies for the mental health of her sister ( a complex choice), and then ended up marrying the man she had loved all her life with the doctor and the sister leaving the picture. But all this only to misunderstand her true love and to sadly remain a single parent herself for 20 years but with her parents.
Ovi - separated from mother as an infant, raised by a dominating grandmother and doting father who tried to compensate for lack of love with spoiling her, developed intense attachment to a childhood friend also growing up without a mother, was given a promise of marriage by the friend, found out after engagement that her fiance actually loved someone else who happened to be her sister, with her habit of getting what she wanted made a wrong proposal to the sister manipulating her love for the mother, could not endure the indifference of her husband and turned to drinking heavily hurting herself and her unborn child, changed over the course of pregnancy with the help of Purvi's doctor husband, lost her baby in accident, was shocked to find that the infant she thought was her child was the child of her husband and her sister, left both the child and the husband, only to find that she was pregnant, hid her pregnancy this time and did not come in the way of the lovers who were getting closer, took care of a sick baby alone but was found by the ex-husband whose accompanying her to the hospital with the sick child created a misunderstanding between then husband and wife, spent 20 years of life as a single mother all alone.
Qualities
Purvi - caring for other people and readiness to let go of personal gain for the sake of the others, especially for Archana
Ovi - ability to grow and learn from past mistakes with admission of her own short comings with humility
Tragic Flaw ("Hamartia" in Greek tragedies - one flaw that causes the downfall of an otherwise good character)
Purvi - can never admit that she can make a wrong moral or ethical choice. She thinks she is always right; and forces others to do what she thinks is right (admittedly it is often for someone's well being) screaming irritably and hysterically until it is done. She jumps to conclusions about moral wrongs of others and even when it is found out that the other person was actually not wrong, she just keeps asking that person "tum aisa kaise kar sakte ho?," (it was astounding when she was asking something to the effect to Onir even as she was in fact getting married to Arjun, the love of her life); she never asks herself, "main aisa kaise kar sakti hun?'
Ovi - in the beginning, obstinate, full of herself and totally self-centered not thinking of anyone else and making an unethical demand for love that cannot be forced, this leads to irritable screaming, self-pity when demands are not met, and excessive drinking. Even after she matures as a person and learns to let go of her own wishes in order not to come in between two persons in love, her stubbornness remains at some level and she is never able to fully open up to her parents, adding to an already complicated problem.
As for popularity, I believe that for TV actors to remain in the public view, they really have to perform in big public shows. Only those who dance or perform in some other way (jokes etc.) in public shows get a lot of attention. From the PR caste, Ankita and Ritvik seem to be excellent dancers. Asha is very good as well. It is interesting that less important characters from various shows appear regularly in the grand public events and are sent to foreign countries for promotion. So, it does not seem very likely that the channel does not want to promote Shruti. She is an incredible actor and I am sure she also has a large fan following, but it may be that she is not comfortable appearing in public shows (here I am only guessing, but that seems like a possibility since she is really good).
Anyway, these are just my views - no argument with anyone. I like both characters but find them both flawed.