Matthew takes Elizabeth to meet his psychiatrist friend, Dr. David Kibner, who is signing his new book at a crowded bookstore. They bump into a friend, Jack Bellicec (Jeff Goldblum), an intense young writer.
Then ... The exterior view of the colorful bookstore reveals the location - it was Bookplace Inc. at 50 Clement Street on the corner of 2nd Avenue in the Inner Richmond (map). Note the small restaurant along the block, Eats, at 40 Clement Street...
... and Now, not long after this scene was filmed the bookstore closed and Eats took over the corner location; it's still there today. Its former space is currently occupied by Shi's Hair Studio.
In the bookstore a distraught woman is overheard confronting her husband for not being her husband - he has changed; she thinks he's an impostor. Kibner (Leonard Nimoy) quickly goes to her and plays down her fears ... "He's still your husband" ... "Will you trust me?".
Then ... As she leaves, Elizabeth stops her ... " I understand what you are trying to say" ... and asks her to call her at her office. She tells Matthew "That man is not her husband ... he is one of them".
... and Now, the two pillars visible near the top, above, are seen in Eats restaurant in the matching shot, below.
Then ... At Matthew's urging, they leave the bookstore. Outside an antiques store across the street Kibner debunks Elizabeth's assertion that her boyfriend has been replaced by somebody else and suggests she is looking for an excuse to get out. Confused, she reluctantly agrees to think about it.
... and Now, back then the store was Golden Era Antiques at 15 Clement Street. The current tenant is the high-end leather goods boutique April In Paris.