I'm not bilingual but I took 4 years of Spanish in high school and then lived in Ecuador for 2 years. I was extremely proficient but not quite fluent. I stutter a lot worse in Spanish, but I think a lot of that is due to anxiety of trying to find the right wording sometimes. I actually did some live translation from English to Spanish for a bit because the organization I was with couldn't find a better alternative, and that went surprisingly well, barely any stutter, but I was in a separate room with audio coming in and out electronically.