Diclofenac sodium is a nonsteroidal anti-inflammatory drug widely used in painful and inflammatory diseases. It can exist in different hydrate phases. Recently the physico-chemical and pharmaceutical properties of a trihydrate form, named DSH3 were reported by the same authors. This short communication discusses how samples of a same polymorphic form can display dissimilar analytical signatures when obtained by different routes. Data from hot-stage microscopy, FT-IR spectroscopy, X-ray powder diffraction (XRDP) and thermal analysis were used to characterise the DSH3 samples prepared by different methods. Through the case study of diclofenac sodium, this work highlights how the method used to prepare a specific crystal modification can generate samples with different morphologies and therefore different properties and physical stability.