Aitch used to look at these Two-Puddly birds and say ‘Why Black-collared Barbet? they should be called Red-faced Barbet!’
There’s probably already a red-faced, I said; and I don’t know why I didn’t go looking then. I suppose life happened.
Listen: Here’s why we called ours ‘Two-Puddly’ (old man Geoff Leslie used to call them Scottburgh – that’s where he would hear them most, at the Fyvie’s coastal cottage).
The Red-Faced Barbet is found up on the western shore of Lake Victoria. It’s duet is a bit less musical, more frog-like, if they don’t mind me saying so:

~~~oo0oo~~~
Black-collared Barbet (Lybius torquatus) – Red-faced Barbet (Lybius rubrifacies)
Thanks – Margaret Elworthy Coombes – for the Black-collared Barbet pic on wikipedia