Can two MESH ID associated with two different sub type overlap or have same MESH ID .


For example 

    Acute M2 Myeloid Leukemia			C1879321	M2	D015470

    

    Acute Undifferentiated Leukemia			C0280141	M0	D015456,D015470



This `

> D015470

` is same for both the subtype.


The answer is yes. In this case, the MeSH term is a more general term for the two more specific concepts. In general, mappings between ontologies are not always perfect 1:1 mappings.