What colour?

[king]

Well one looks like a blue grizzle. The other looks like either being a Dun or maybe a Brown (the rarest of the the 3 base colours)
It's hard to give correct colour until the birds first moult. And if still in doubt you may have to breed from it to be certain. As many birds are not genetically the colour they appear to be.

Below is a brown I bred a few years ago.

[king]

How did or what did breed that brown king

Mine was bred from another brown Neil. The brown gene is not common in Racing pigeons. Brown feathers will fade into a cream color and then fray with age by the suns rays. This is why Brown is not commonly found in most racing lofts. Brown wing feathers also do not hold up to the stress of racing.
All pigeons come from only 3 base colours. (1) blue/black, (2) ash red & (3) brown. with the most dominant 1, then 2, then 3.

[king]

How did or what did breed that brown king

Mine was bred from another brown Neil. The brown gene is not common in Racing pigeons. Brown feathers will fade into a cream color and then fray with age by the suns rays. This is why Brown is not commonly found in most racing lofts. Brown wing feathers also do not hold up to the stress of racing.
All pigeons come from only 3 base colours. (1) blue/black, (2) ash red & (3) brown. with the most dominant 1, then 2, then 3.

I don’t think I have seen one before
What would a chocolate come from as a base colour is that brown or red base

It can come from ANY of the 3 base colours.. A Chocolate is a Recessive Red. A recessive red will require two genes (factors) to show itself. So unless your birds have the recessive gene your very unlikely to breed one. Many chocs/recessive reds in the Mulemann family can come from two non-chocs where BOTH parents carry the recessive gene.