While these cards do grant additional types, which could be interesting in Typal decks, they otherwise seem rather lackluster
But there is no specific keyword for it
The impact is minimum, as many times it can be an easily overseen detail, or it can have the best of the outcomes, by making something more visually understandable without messing up basic concepts
Here let me show you: This is Cruel Edict and Imperial Edict from the various Portal sets
You have to be very lucky indeed to even see all the premium on colour duals, you have to be even luckier to see them in packs where you don't have important picks for the straight Izzet version
This can be especially potent in decks like Zombie Typal, which have a natural affinity for sacrificing their own creatures