Yeah, this happens a lot.
Met a Taiwanese kid in college. He grew up in an Italian American area in NJ. He had the HEAVIEST Italian American accent... it was hilarious. (He fixed it over the years).
I grew up in NY and took French in high school. Had a heavy American accent. Then I moved to Quebec for a while, and took French lessons from a Spanish woman. Then I studied in Lyon for a little bit.
When I started working in Paris 2-3 years ago, I always got asked what the fuck my accent was. (I'm Asian).
I have a southern French accent mixed with a Spanish accent while using a lot of Quebecer slang and phrases.
Yeah.. my french is fucked up.