Q: migration to Fotos and icons does not correspond to the batch, a really mix up

Yesterday I'v done the migration from IPhoto to Foto. I check the right library of IPhoto, it took some time to move about 31.000  foto. At the end It was a shock. When I try to open an album, there is a first upload of right foto corresponding to the album and a  second later, new ones showing a mix and the first ones disappear.

The icon on the left does not reflect the foto. I have to click on a single one to see all correct.

It's a mix up..what can I do?

The only positive thing is that I can see Eventi IPhoto so I can choose what I wish and how I remember them.

Is anybody that can help me?

I updated my MacBookPro (half 2009) to El Captain (after Yosemite and a former Snow leopard).

The technical support told me is a vintage Mac. ah

It's terrible seeing al these photo mixed up.....