Possible, but unlikely given the pain that would likely ensue.
There's a good reason why most animals with horns (and generally only the males) develop their horns at puberty; live birth.
When you get right down to it, the advantages that horns provide in combat and display to females is counterbalanced by the difficulties they would present during birth; a smooth head is what you really need for a species to find it easy to birth the next generation. Evolution has solve that by providing smooth crania for the young, and horns / antlers for the mature.
As such, antlers and horns generally tend to form symmetrically in the same way as the rest of the body. This is the primary reason that most species have two horns or antlers instead of one.
In the examples you provide above, there are really only two possibilities for how this could manifest;
1) Birth Horns
If your creature is born with the halo horns, then either they're smooth so that 'thorns' don't impede the live birth, or the thorns and other manifestations on the halo appear later, during puberty. In such a case, these offspring would be different to the two horned species by necessity; being born with two horns would present serious issues for the mother so these specific offspring would be immediately different from the mainstream members of the species
2) Puberty Horns, but fused
If the horns manifest during puberty, then it's possible that the horns grow towards each other and fuse during maturity. These would be simpler and easier to explain from an evolutionary perspective, but would no doubt present painful situations for your halo antler recipients as they would firstly breach the skin as part of the normal horns, then fuse later on once they've grown to a certain size.
Realistically, if 'halo' horns were a reality, then your concept of being born with a horn (or bone) halo which 'breaks' in certain cases would seem to be the most plausible solution to this. That said, such an evolutionary trait is unlikely as it would introduce additional complications to the birth that make successful delivery less likely, not more. As such, the current model of no horns at birth, then growth at puberty seems far more likely than the model you present.
It should also be noted that halo horns are unlikely to develop in any event in an environment with intelligent predators / hunters because humans realised pretty quickly that horns and antlers give you purchase for snapping the neck of your prey if you've wounded or disabled it at some point. In other words, such horns present a combat and predatory weakness that other animals would exploit if at all possible, and the ability to present to females only goes so far in offsetting that weakness.