Yes, they have separate Japanese Wikipedia articles:

"American Coffee": https://ja.wikipedia.org/wiki/%E3%82%A2%E3%83%A1%E3%83%AA%E3...

Caffè Americano: https://ja.wikipedia.org/wiki/%E3%82%A2%E3%83%A1%E3%83%AA%E3...

The "American Coffee" article introduction paragraph even clarifies that this is a completely separate thing from Caffè Americano.