09/18/2026
When training data has duplicates, your model pays twice. Once in wasted compute, again in worse generalization. Exact matching catches true copies fast with hashing. For near-duplicates, MinHash with LSH or embedding-based clustering scale fine using Datasketch, text-dedup, or NeMo Curator. One nuance matters: aggressive dedup on training data lifts quality 5-15%, but eval data wants exact matching only, so you keep leakage detection intact. Low effort, high return.