Redundant MeSH mappings

[ireneisdoomed]

Describe the bug
There are 1156 terms in EFO that have a mapping to multiple MeSH terms. The majority of them (1123) are duplicates.

Observed behaviour
We observed this in the disease index we extract from the EFO slim.
In the cross references field, MeSH is mentioned in 2 different ways: MeSH and MESH.

When we looked at the IDs coming from the 2 references, we observed that 1123 out of 1156 of them were duplicates. Some examples:

+-----------+-------+-------+----------+
|         id|   MeSH|   MESH|equalOrNot|
+-----------+-------+-------+----------+
|EFO_0000508|D030342|D030342|     equal|
|EFO_0007136|D000377|D001072|  diferent|
|EFO_1001117|D017562|D017562|     equal|
|EFO_1001175|D010302|D010302|     equal|
|EFO_0003902|D016103|D016103|     equal|

Expected behaviour
To have the MeSH references grouped together.