Chat/Combat log split
no idea, I would sorta wonder if it is a third pt proggy monitoring the chatlog and filtering into two different overlays.
if youy use ffasist or similir programs but espacialy FFasist2 its easy to have tell/party/linkshell /other in diffrent windows, you can really break any paticular messege to be in a specific window if you want to go that far with super custom programming, which is really just simple scripting