Am I imagining this 'harmonica'?

[goingdownslow]

In the '60s I recall seeing adverts for a harmonica, but instead of the row of holes it had three mouth pieces on. I think it was for playing 12 bar blues on, but again I might be making that up. I have never seen or heard of it since, and over the years have mentioned it but no one recalls it, until yesterday when a friend of mine described seeing the same thing.
I have googled all sorts of terms but have come up with nothing. Did we both imagine it?
A very rough sketch is something like this....