All the time. ALL. THE. TIME.
all day every day
I always do that when I speak English and German (never Swiss German, though), and I don’t find it awkward at all… ;-P
ETA: Wait. Actually, that would be variation, not accent. I don’t copy accents of people who aren’t native speakers XD
it happens to me in all the languages I know D: sometimes even when they’re not native and talking wrong I’m using the same mistakes because my subconscious is telling me they’ll understand me better ._. *total failure*