Edit: I noticed you put in the unused bitmaps the MI Cuirass of Keres. Was that intended?
No it isn't intended. The same bitmap is shared by one unused item which is of Legendary type:
ArmorProtective_UpperBody=Legendary=tagArmor_pieces_torso==RECORDS\XPACK2\DEV\TESTITEMS\PIECES_TORSO.DBR=XPack\Items\EquipmentArmor\Torso\UIBitmaps\mi_l_keresmelee.tex
Because of above item it got there.
Following item also shares same bitmap, but I don't understand this entry:
ArmorProtective_UpperBody=Rare=xtagMIArmor044={^l}Anaplekte's Cuirass=RECORDS\XPACK\ITEM\EQUIPMENTARMOR\Z_TEMPBITMAPDBRS\MI_E_KERESMELEE.DBR=XPack\Items\EquipmentArmor\Torso\UIBitmaps\mi_l_keresmeleeM.tex