This would be a real mess to check. I bet there’s a really small overlap for some pairs, like Egyptian Arabic vs. Japanese*; but for others the overlap is rather large, like Hindi vs. English. And sometimes counting if you can speak a language or not can be tricky — like, how much Spanish does a Portuguese speaker need to learn, or vice versa, in order to be considered “speaking” it?**
*I can think on at least one example of that, though: Fairouz Ai. Two if her brother also learnt Arabic.
**The Venezuelans (mostly ES speakers) in my city (mostly PT speakers) come to my mind. Sometimes their portuñol is easier to understand than some Portuguese varieties. Do they “count” as speaking Portuguese? No idea.
This would be a real mess to check. I bet there’s a really small overlap for some pairs, like Egyptian Arabic vs. Japanese*; but for others the overlap is rather large, like Hindi vs. English. And sometimes counting if you can speak a language or not can be tricky — like, how much Spanish does a Portuguese speaker need to learn, or vice versa, in order to be considered “speaking” it?**
*I can think on at least one example of that, though: Fairouz Ai. Two if her brother also learnt Arabic.
**The Venezuelans (mostly ES speakers) in my city (mostly PT speakers) come to my mind. Sometimes their portuñol is easier to understand than some Portuguese varieties. Do they “count” as speaking Portuguese? No idea.