I think I've figured out what happened.
After looking at both side-by-side very closely, I am certain that every card in both packs was printed from the same plates, except for the 6 and the As de Baton, and possibly the Reyne de Baton.
The Lo Scarabeo pack does not have a 6 de Baton, so they took out the middle Baton of the 7 to create it. You can see that they are otherwise identical; see in the faded areas at the ends of the Batons for example.
The shading strokes in the right "stump" of the As de Baton are quite different from the Héron, and the overall impression seems to me to be different. It could be just a much thicker inking, but I don't think so.
The remarks for the Reyne are kind of the same - not sure she is different, but I have a sense she is.
Finally, in the Héron it is the Valet de Baton who gets the "Nas. Conver/France" along the edge of his card, while in the Lo Scarabeo it is the Valet de Deniers.
But overall, the two decks are from exactly the same moulds, except the colouring varies significantly.
If you look at the Roy d'Epée, you can see he is holding a sceptre in his left hand. In the Héron you can see the pommel, but in the Lo Scarabeo, it is covered over in red. However, looking closely, you can see the outline of the pommel underneath the red.
My impression of identical plates is confirmed especially by the suit of Epées. If you look at the black parts in both decks, the blades I suppose, you can see the irregularities in the ink, that must have been caused by the wood grain. In both decks the same irregularities occur (i.e. little holes, impressions of circles and other shapes, artefacts of the wood grain itself) in the same places. This shows beyond doubt that they were printed from the same wooden plates.
Ross