The early Italian coinage from the instep of the "boot" of Italy is very distinct. The reverses frequently mirror the obverses but incuse, rather than relief. Dating to the period c. 530-510 BC four of the obove five coins show this trait.
The top two are from Sybaris, the middle coin from Croton and the bottom two from Metapontum.
The question arises why the distinctive relief/in use mirrored design? It has been suggested that it aids the stacking of the coins. That hypothesis doesn't really stand as, unless the sided of the coin are identical, they won't interlink. With hand made dies/punches this is not possible.
One of the more intriguing suggestions is that their introduction is linked to the exile of Pythagoras from Samos. His father was a gem engraver and the skills of a coin die engraver are very similar. Pythagoras was exiled initially to Croton and then Metapontum around 530 BC and so the approximate timings are right. It is a possibility that this individual was responsible for the introduction of the distinctive coin design.