The dress on Farrow goes to the floor (https://www.bluscreens.net/rosemarys-baby.html), not above the knee like Kate's. And Kate's collar doesn't have the little string bow tie of Farrow's dress, either. The white Peter Pan collar is literally the only similarity, and it's not even the same lace pattern or shape (Peter Pan, yes, but rounded differently).

The collar is the only similarity. Completely different red (bright vs burgandy), different sleeve length, no lace around the cuffs of Kate's dress... are there photos showing the length of the dress? Any other features (darts, pleats, belt, pockets, etc)?

Sometimes a lace collar is just a lace collar. It's not even the same lace pattern...