Duby (NZ) (Ocean Park) broke through for her maiden win at Cambridge on Wednesday after taking out the Paynters’ Catering 1300. Aided by apprentice jockey Joe Kamaruddin’s three-kilogram claim, Duby was last of the pack and six lengths astern at the 600m mark before circling the field and sailing home over the top of her rivals to win by 1-3/4 lengths. “I’m happy with that,” trainer Jamie Richards said. “I don’t think she saw out the 1550m when chasing a hot tempo here last time. We gave her a freshen-up,…