Which POA will they honor?

Are you the mother of the grandson?I

Is the new POA also Durable?

Our mother has assigned one brother Healthcare POA and one is Financial POA.

So neither one is overwhelmed, I imagine. As as girl, I am not considered 'capable' of being a POA, which is fine, I don't wanna be.

As long as the 2 POAs get along and they are caring for mom, then I wouldn't fuss at it. It's a thankless job and often comes with a lot of baggage. My HCPOA brother is very aggressive and secretive at the same time. He takes mom to the Dr and doesn't share with the rest of us her health issues. His JOB is to protect her interests and be the family go-between. Instead he has become her 'voice'. If he doesn't want her to have/do something, she cannot have/do it. Although we all believe she is perfectly safe at this point (quadruple vaxxed against COVID) he will not allow her in public places. So other than the Sr Center for 60 minutes once a week, she is not allowed out of the house. Yes, she goes 'grocery shopping' but brother makes her stay in the car in the parking lot while HE shops. He has minimized her sense of control to the point no matter what you ask her, she says "let me talk to R first". He has not allowed her to get a haircut or visit another family's home for almost 2 years.

It's ridiculous, but she kowtows to his 'powers'.

The FPOa simply meets with her once a quarter, goes over her small investments and checks her checking acct to make sure she's OK with it. He gives her a certain amt of cash so she can't give it all away in the first week of the quarter, but that's it.

She does not have dementia other than what ANY 92 yo woman has.

Cheyanne, at one point you called this the "financial daughter". To me this means she has been doing the financial work on a legal POA for some time? And the grandson has not? If the grandmother was able to understand in an attorney's office that she was appointing her daughter to handle her financial affairs that would have been enough. While my brother had a diagnosis of probable early Lewy's dementia he made an ironclad POA, Trustee of Trust with me in his attorney's office. In the years I managed it for him I had not a single question from anyone. The attorney examined him so completely that he asked him alone and with me questions and said in front of me "Do you trust this sister with you LIFE and every penny you have, because when this is done she will be able to sell the gold out of your teeth" and he said that he did and passed all qualifications for making these papers.
Your grandson will have to go to his own attorney if he is not able to discuss this with the daughter, which would be sad. But as things currrently stand, if this daughter is doing POA "financial" work of paying for bills and getting every penny in and out of grandmother's estate accounted for, and can prove this, not a lot else will occur. She may feel forced to file for guardianship to prevent meddling in all of this.
Do you have REASON and PROOF of intent to defraud her mother? If so, consider filing with APS.
It is always sad when families cannot discuss this sort of thing. Trying to sort these things out legally is costly and a true mess that makes a senior feel divided and unhappy when they should be protected.
Cannot know what you suspect this "financial daughter " of; only you have that information. You may need to take it to an attorney for advice.

Are there two POA's? One for medical and one for financial? If so, both may be valid.

Was she competent to change it?

Cheyanne, attorneys I've worked for always include a clause that "any and all previous Powers of Attorney are hereby revoked."   

I don't understand why the grandson took a POA document to a doctor for signature, especially after an apparently legitimate one already existed.   I also don't understand what a "finance daughter is." 

The people appointed to act are "proxies". 

Typically, a POA or DPOA (Durable Power of Attorney) are prepared by attorneys; they know the law better than a doctor.  

Some hints to understand POAs:

They're documents, not people.   A grandson or daughter aren't POAs, they're PROXIES, which mean they can act on behalf of someone.  The only POA is a document.

The designated proxy/proxies can present a properly executed, witnessed and notarized POA or DPOA to someone, for validation that the individual can act on behalf of the person who created it.   I'm assuming that's why the grandson took something to the doctor, as certainly the grandson could not ask the doctor to sign as he's not the principal, the one who created the document.

Hope this helps.

Sign what papers. A doctor doesn't sign a POA. He writes a letter to have a POA changed from one in which a COMPETENT elder directs his own care to a POA in which an INCOMPETENT elder is cared for by the person they signed up to be their POA.
The newest POA is the one that is in effect. If the POA in 2020 assigned a grandson and was done by an attorney, has the grandson been currently ACTING as the grandmother's POA? Has the Grandson shown the POA to the daughter. You call her the "finance daughter". There is no such thing as a Finance daughter. There are POAs and there are guardians. If the daughter has been handling the POA, and she already has letters from a doctor done in 2022 then I ASSUME she has a POA done in 2022. If this is a legally done POA then the newest LEGAL POA is the one that is in effect and cancels all others, and there is usually language included in the POA to say so.
So now, whether or not all these people "get along" it is legally crucial that the grandson and the daughter get together and compare the POA. The grandson believes he has one. If the daughter is handling finances then it is likely SHE has one and a newer one.
And of course WE here on Forum cannot tell what the case is. Only the grandson, the daughter, and you can find this out. Wishing you good luck.
the real danger here is if the grandson attempts to use his POA to sell property or access accounts when he has no right to do so. This is legal business with legal fiduciary consequences under the law. Time to find out what's going on.

They will honor the most recent POA. That's the law.