"Special" Christmas Gift for My 2Nd Daughter

a sled with her name engraved is something special that you might want to do for her for her first, they will be able to keep this & will want their own, even a rocking horse/lamb, if it is one they can keep & even use for their kids then i would repeat that too, the other gifts like a kitchen/doll house i can see how you might not want to repeat those...what about a child size wooden rocker (you could have her name put on that too), or a nice wooden cedar chest, she could use for toys now & other things later (like blankets, or eventually a hope chest)...

A nice wooden toy chest with her name or monogrammed initials, perhaps with a whimsical painted decoration or big cabbage roses.

Wooden children's piano
Children's wooden, fancy art/painting easel.
Wooden wagon
Wooden train set
Carved, wooden music stand
Children's picnic table & benches

(I am sitting on my daughter's bed, looking at my wooden bunkbed doll bed which I got from Santa when I was 4 and which I gave her last year. I wouldn't give doll furniture to a 1 or 2 yo--because of the tendency for the child to try and climb/sit in it and break it. But perhaps on a future christmas, you can consider wooden doll furniture.)

I like the idea of a nice wooden toy chest with her name engraved on it.

a baby bed for her babies

It matters to me too, so I totally get it. How about an engraved baby bracelet? Every year for my baby's b-day I am giving her a special pair of earrings (she only wears them on special occasions, and each year is a new stone). good Luck!

Give her her own engraved sled like you did her sister so she has one too! It could be the same (or similar), or completely different if you want. A different color, different design, or different calligraphy could set them part. It could be a tradition that your babies get THAT as their first Christmas gift. :) It sounds like something they may keep and pass down, so they each deserve their own, IMHO.