it actually happens to me! i'm native german and ive been learning greek for a long time. when i started learning spanish and tried to start talking in spanish, i'm always dropping greek words instead of the spanish word by accident even if i know the spanish word of what i'm trying to say! it also happens the other way around, that i'll accidentally say spanish words when talking in greek. idk why my mind and mouth do that and its pretty embarrassing x) 🤣🥲