To reproduce:
In a schematic, place two resistors of the same value & type. Select one, and unmount it. Now export the BOM. There will be only one row for the two resistors, and the mounted column will say 'No'.
To fix:
Separate mounted and unmounted components of the same type, each on its own row.
Vivaldi
1.95.1077.55
Linux
EasyEDA
5.8.20