You remember correctly! AR had suggested casting the same actor for the role 2/16/17:

Also Anne can you please spell it Nicolas w/o the H? Plz? *cries*
Lestat did compare Nicki and Louis, and there are similarities and differences, I think AR was just curious about it as an idea… I’m sure this has been done in live theatre at some point, casting one actor for 2 (or more) roles in a given production. She did say she’d want a talented, versatile actor who could create each role distinctively. Twins could probably create distinctive personalities but they would probably still look basically the same.
However, that “twin” comment from TVL was more about their personalities than physical resemblance:
I fell fatally in love with Louis, a young dark-haired bourgeois planter, graceful of speech and fastidious of manner, who seemed in his cynicism and self destructiveness the very twin of Nicolas.
Nicki’s face is not really described, aside from his having brown eyes. Louis is described in much more detail: narrow face, wide-set green eyes, wavy/curly black hair.
Louis and Nicki are not the same. I feel like looking the same would overpower distinctive personality differences.
Played by the same actor or identical twins, I feel like it would seem too much like “Louis”/”Nicolas” is trying to trick Lestat, a weird consideration I’d rather not have introduced.
…But let’s have the Sprouse twins audition anyway and let’s take one of them!