Re: Mantella baroni introgression? Very picture heavy!
My guess is they are all Mantella baroni, especially after listening to the captive-bred one call in the video (it is a single one note metalic dink, not a two note chirp like you would expect for madagascariensis). Mantella baroni are really variable, not all will have a single dot on their chin, although I agree it is kind of unusual to have a group with so many characteristics which seem to be in-between. That said, you really won't know with certainty what species they are unless you know where the wild ones were collected or go ahead and do the genetic work.
I also think it is interesting the captive-bred ones have such unusual coloration. This can be an issue for other captive frogs too, including other mantellas. For example, how many captive-bred aurantiaca do you see with red flashmarks? Often they are missing or washed out and yellow. Often captive-bred mantellas are faded and less intensely colored than their wild counterparts. Maybe it relates to diet of breeders, tadpoles, or juveniles as they grow. In this case, it is almost as if they captive-bred baroni are not losing their juvenile coloration even though they are now adults.