They come from Siscia. I have a few. This one is probably quite scarce without mintmarks to identify the mint.
Here we have the most difficult question of the specialist. I'm not a Probus specialist and am not home right now so can't refer to books (if it is even answered by the old, old RIC 5-2). I see two coins of different style so I might suspect one is Siscia and the other Serdica or some such difference. If I WERE a Probus specialist, this sort of thing would make a big difference. Even in the specialties I claim to care about, I get little thrill out of coins combined oddly or with a PF more or less. I'd be similarly unimpressed by a coin adding a KA to the officina letter or not. Do I know? No. Do I care? I might if someone explained to me why I should. Right facing consular busts are scarce, I get that. In my Septimius specialty wrong way portraits are downright rare and I am really happy to have what I have. I care. What I do care about here is the second coin has what I consider more pleasing style. It is not the finest facing quadriga I have seen but it is nicer than the other. I do have a preference for the type with flames under the horses (not shown on either of these). Silly? OK. Back to the BIG question: Should we care? I would love to have a horsehead obverse even if they were as common as dirt. I even care for extra fancy Probus shields with scenes on them even though they are somewhat common. I'm fond of the EQVITI series even though a set can be assembled by anyone who cares. Educate us: What makes one of these coins worthy of our care?
I still think that the 2 shown earlier with consular bust right are both notice-worthy even for someone who's not a Probus specialist. Not for obscure reasons but rather for the obvious fact that such busts facing right are conspicuously rarer than the normal Probus-style bust.
@dougsmit You could be right. They appear on Wildwinds coins, but they are not described. I have got "clouds" from somewhere, but I don't remember where!