I'm not fluent in Tulu, the language of my native land. And still less in Malayalam, my hereditary language. By linguistics, I am actually a Kannadiga. But when I converse in Tulu , I tend to mix Malayalam verbs and cases sometimes. Never Kannada, except for nouns. However, I haven't observed that phenomenon vice-versa(no idea if I missed noticing it). I of course don't know if this signifies anything.