Single Delivery for multiple reservation

Hi,

I am trying create outbound deliveries for open reservations through MB26 t-code. I selected all entries and posted. After the deliveries got created, I found that in some instances, single delivery is getting created for multiple reservations. For example, in one case, one delivery is created for 3 reservations (created for 3 work orders).

Can anybody suggest why system creates one delivery for multiple reservations?

Thanks

SB