Had a mix up possibly occurred?

7. Both Mrs. Smith and Mrs. Jones had baby girls the same day in the same hospital. Mrs. Smith took home

a baby girl, whom she called Shirley. Mrs. Jones took home a baby girl named Jane. Mrs. Jones began to

suspect however that her child and the Smith baby had been accidentally switched in the nursery. Blood

tests were made. Mr. Smith is Type A, Mrs. Smith is Type B, Mr. Jones is Type A, Mrs. Jones is type A,

Shirley is Type O and Jane is Type B. Had a mix up possibly occurred?