By having two individual boards which ultimately will produce two unique individual tones we get many more people building one or the other. 10 years ago we used to have just the phaser board and list a particular mod called “the vibe mod” Unfortunately at the end of the day nobody bothered to build the vibe which was a shame.
Giving “The Vibe” circuit a name all its own resulted in people actually building it and it is certainly worthy of adding to anyone’s pedal board when built to those specifications.
Incidentally the vibe tone is a sound you would hear familiar to that of Robin Trower or perhaps Jimi Hendrix and is quite different than a traditional phaser tone.
So that is the “real reason” there are two unique circuits with two different names that could technically be built on a single board.