Fans may recall that the character of Lore was first introduced in the 1998 “Next Generation” episode “Datalore.” Spiner became adept at playing opposite himself. Using compositing VFX technology — or sometimes just clever editing — Spiner could play multiple characters in the same room. In the 1990 episode “Brothers,” he pulled triple duty, playing Data, Lore, and the elderly Dr. Noonien Soong. While making these multi-Spiner episodes, however, the directors were always careful to keep Spiner in distinct costumes, allowing audiences to known which Spiner they were looking at in a given moment. He would film the scenes as one character, acting opposite stand-ins, then change outfits, and do the scene again.
For “Picard,” however, Data and Lore were both abstractions of the same Data, meaning that for the first time, they wore the same costume. Also, their scenes were merely face-to-face conversations in a white void, so there was no set to move around. As long as this was true, Spiner was allowed to play both parts without any edits. The actor described it like this:
“[T]here was somebody in costume and makeup for me to look at [on ‘Picard’]. But there were times in that scene — and this I have never done before — where I would leave the frame as one character and literally come in the other side of the frame as the other character. And there were no cuts. The camera was moving and I was moving and I would just be the other person. It was a challenge! It took an entire day to do that scene and it was a challenge.”
Only voice actors typically have to play multiple characters simultaneously. Live-action actors rarely get the privilege.