I think it is probable that "Rose du Roi" and "Rose du Roi a Fleurs Pourpres" have been confused from time to time. And I think there certainly is a at least one rose with dark purple flowers that has a more modern look to it that has been sold under one or the other of the names above for some time. I notice that Vintage Gardens sells two roses under the moniker "Rose du Roi" which they subtitle "(of commerce)" and "(original)." These they list as Damask Perpetuals, as they seem to fit that description well. They also sell "Rose du Roi a Fleurs Pourpres" as a Hybrid Perpetual. Here, again, their dark purple rose has the long petals that impart a modern look to the rose, especially in bud. This organizational schema solves most of the more serious practical problems of distinguishing these three different cultivars from each other going forward. While it might be inconsistent with some of the history, it's clear that the history of these roses has some inconsistencies and/or missing information.

I notice, too, that if all the photos of the dark purple rose with long petals listed here under the two entries that contain "Rose du Roi" were moved into "Rose du Roi a Fleurs Pourpres" and all the ones that depicted a more damascene flowers in crimson tones were moved to "Rose du Roi" most of the glaring problems with the photos would go away. We may never know what has actually happened, but it might be possible to make things a bit clearer for future rose growers. Just a thought.