Being in the same town gives rise to the possibility that they could have met at some stage being of like minds literally. Also the ESP of Mary would have made her more likely to be a person of notoriety within the town. This could lead Lurancy to develop the alternate personality of Mary after her death if it wasn't a true case of possession.
Both Mary and Lurancy suffered with what seems to be mental problems due to possible
Dissociative Identity Disorder and Epilepsy, these factors do indicate leanings towards ESP and psychic phenomena, specially if Mary had a brain tumour from which she died. Augmented