Not a big deal, and likely any perceived negatives of brand confusion (which is mostly vibes, even if they have research) are made up for by improved operational efficiency.
Graphics hub doesn't have to create deliverables for old, new, and alternative looks, one of which was only used by two stations at most. (Which would explain the order of the rollout so far, to minimize time with 3 active looks in use)
When sharing content, preproduced graphics inside a story don't have to be re-made when shared between the two stations.
Once everyone is on the common look, depending on how thourougly their ENPS and graphics systems are interconnected groupwide - it is entirely possible supers or fullscreens for groupwide content (DC bureau, special projects, etc.) could be stored in a common location and dragged and dropped into any station's rundown.
And let's be honest, most of the people who nitpick aesthetic music and graphic elements of TV newscasts are, well, here.
I worked at an operation that did two brands of newscasts with different graphics. Workflow headaches for everyone. If I had a dollar for every time the wrong graphic look popped up or wrong brand name was said in a reporter track on the other station, I would have had a respectable secondary income source.