Update:
I found another coin in the 24 seed, 45$ worth of BabyDogee
So overally:
120$ worth of Doge
45$ Babydoge
I can see first transaction to the wallet made by August 2023.
Its clear someone have the same 24 seed.
I see Only 2 option now:
1. 24 seed generated completely Randomly and Both device got the same seed. But its very unlikely
2. Ledger use pre generated 24 seed and probably due to an error both device got the same 24 seed. This senraio is more likly to me.
But again I have no any evidence.
Are you kidding me or something, I don't think that your sister bought this ledger waller new maybe she bought it from someone, because it clearly shows that the seed phrase is already in use and belongs to someone else.
It is better you abandon the wallet and buy a new wallet but not Ledger product this time because it has become a close source wallet and they are in charge of your seed phrase.