Chanel, you answered your own question when you said the crumbling brick fireplace can’t be left “as is”. There are two fireplaces because that large space used to be two rooms with a wall between them. The crumbling brick fireplace needs to be removed completely. You will probably rent to a family at some time and it will become a liability if it is not dealt with now. If it is crumbling where you can see it, it may also be crumbling where you can’t see it (the chimney, for example). The room will also look and function better with only one fireplace.

Yes. Just remove. It doesn’t look right. The other will look even better if that one is removed AND as was mentioned, if it’s crumbling already and you’re going to rent it out, the last thing you’d want/need is someone getting hurt. Do it now while while it’s easier

Yes ..to removing the fireplace ...! and I would partition the entrance with a small wall ..up to the window or just towards the end of the front door ..so that when you come into the house ..you don't walk straight into the living room ..and it would give you a place to finish off the living room ...with paintings and or furniture ...and you would provide a lovely entrance room with a mirror ..a small table ..to put keys ..maybe even a closet or an area for coats .., boots ..
Yes, looking at your great room again ..I would definitely get some Sheetrock and get started on a partition ..creating that needed entrance space .....and separation ..for the wonderful living room , after you take out the fireplace ..GREAT project . !

Another yes...remove one fireplace. I would "not" partition the entrance...leave it open! Open concept is just THAT....

I would remove them both. The room will work better for furniture placement.

Thanks for the feedback everyone! Yes, the rooms were originally partitioned off and the other unit actually still has the original pocket doors that separate the living and dining space. I love that feature but I will not be adding it back to this unit as I also love open concept spaces. Both chimneys were inspected with no concerns. I probably should have clarified it’s structurally sound but the face of it is crumbling so this is primarily an aesthetic fix. The working fireplace is gas so I think we are safe there too. I have the general consensus so now I need to determine what design idea to go with...decisions, decisions.

Well, I would get rid of it. But it will not be cheap. The plus is that the flooring is running in the same direction as the hearth, so it won't be too hard to install hardwood.

I would repoint the brick one (it's the gas/working one correct?) take the wood mantel off the dining room fireplace and add it to the living room and wallborad over the dining room fireplace.

Remove the brick one ..it looks odd ..keep the other one

Because you’re dealing with a heritage property I would have a mason in to fix it. You could be opening up a can of worms when taking it down and it may be a simpler fix than you’re thinking. It doesn’t need to work just safe! I think you’re best to talk to your towns historical society because I know where we are it would devalue the property big time.sometimes the easiest answer isn’t always the best!

It looks as though the dining room fireplace has an old gas heater in it. If the chimney is in good condition, why not have the face of the fireplace replaced/repaired and install gas logs there, too? If you live in a colder climate, the supplemental heat might be appreciated by your renters, especially if the unit is not well insulated.

There may be electric units that would fit there, too. You might check Amazon since most anything can be found there.