Duplicate Material Codes for Mining Equipment Spare Parts: Types, Causes and Governance

Duplicate material codes, where one spare part has several codes in an ERP system, fragment stock and lead to repeat purchases, yet why they persist in maintenance spare parts is poorly understood. This paper treats duplication as a failure of item identification and distinguishes three layers of material attributes: identity (manufacturer part number), description (name, language, format, unit) and application (host equipment). Using 10,396 mobile equipment spare parts codes from a nickel–cobalt mine in Papua New Guinea, part-number screening found 250 duplicate groups covering 5.0% of codes, 97% of which split stock across codes. Three mechanisms were identified. First, descriptions diverge so widely that an exact name match would detect only 6% of the groups, against 92% for the part number as recorded. Second, 48% of the groups span different equipment groups, showing that coding by host equipment repeatedly recodes common parts. Third, duplicates accumulate over time and are more frequent where descriptions mix languages. Governance should therefore use the part number as the identity key, standardise descriptions, and record host equipment as a where-used link rather than as grounds for a new code.