The two styles of bricks do seem to be part of the same pavement. Mixing the rectangular and diamond bricks is not well-attested (or attested at all?), and we will need to look for comparanda. This could be evidence of experimentation, an aesthetic choice, reuse of available materials recycled from other pavements. It is clear that someone invested in a substantial pavement in Room D after the mid-1st c. AD fire event: the pavement is functional but aesthetic.

Remians of a floor surface consisting of diamond shaped tiles. Originally we thought this was an earlier floor beneath the Opus Spictatum (20091.) While this interpretation is still plausible, could the diamonds and herringbone be the same floor? Creative floor Innovation at Marzuolo? - EBS