Multiple pulse is sometimes used in literature. It seems to be, that the term has either a trivial meaning, as Audioguru guessed,
or is designating arbitrarily specific techniques, but can't be understood as known technical term.
So if you are intending something special, clearly tell what it is.
I think your referring to a quasi sine wave, its a look like a sine wave but its composed of pulse to represent the sine wave. With this multiple pulse you can filter it out to great a smooth AC sine wave. The draw back is that you need a lot of voltage supplies to create to voltage references, which is not ideal for an inverter to have.
It is better that you used H-brigde design to create your multiple pulse, but you need a very good LC filter to have an output of sine wave.