If a daughter takes a DNA test with her aunt who is her mother's identical twin, the results will show a relationship that is essentially the same as the mother-daughter relationship. This is because identical twins have virtually the same DNA.
Since identical twins share nearly 100% of their genetic material, the genetic test will not be able to distinguish between the mother and the aunt. The results may classify them as either mother-daughter or very close relatives, as the aunt’s DNA will be indistinguishable from that of the mother.