I was still thinking about this and it (finally!
) dawned on me that maybe you have a lot of double and triple -nosed bulbs. These are bulbs in the process of dividing, so they have more than one growing point (nose), but haven't separated at the base yet. If so, all the more flowers in summer!
Otherwise I can only think that maybe the leaves have separated at the top of the shoots already, giving the impression of multiple shoots when in reality there is only one.
But anyway... they're planted and you'll soon be enjoying a beautiful, fragrant lily garden.