IN HER OWN IMAGE by Anna Murdoch (Morrow: $15.95). Here is yet another tale from the Australian outback, where men are men and women are more than a little neurotic--if the three principal characters here are typical examples. This first novel by Anna Murdoch (wife of Rupert) features an unscrupulous mother, who never stayed home with the gals when they were young and plagues them now with her spitefulness and eccentricities; her elder daughter, Liz, tipped-lipped and long-suffering, and younger daughter Josie, self-centered, selfish, beautiful--and so like her mum. Guess which one mother loves best? Of course, the beautiful Josie, who, after an absence of 12 years in New York City, descends on the family ranch to get what she wants. What she wants is Harry, who, rather inconveniently, is her sister's husband. This is not to say that Josie doesn't already have a husband--and a son. And Harry is in a curious predicament: He loves both women. Who wins? Who loses? Visit the outback and see.