Well, sort of, it's more like two previous characters as one character, like in Melty Blood
In the summer of this year, exA-Arcadia released a rather surprising sequel in Chaos Code -Nemesis Experiment- (shortened to Chaos Code NEXT). It's a fairly mild update, simply updating Chaos Code and most noticeably adding 3D backgrounds.
However, it's now getting new content in the form of a new* character. You can find the trailer for it in the tweet below.
The asterisk is there because it's technically two previously existing characters, Hikaru and Kagari, but combined into one, sort of how you had combination characters in Melty Blood, but from the trailer, the application seems more limited here.
All the footage shows that there is main character that you seemingly choose for the duration of the match or the round, with the second character coming in only during certain super sequences.