Another way I have thought about this, coming from a religion that believes in "Oneness" and in Reincarnation (Sikhism), does reincarnation have to necessarily happen linearly in time? If not then there is no reason that there would have to be an upper limit on the number of beings as you could have multiple of the same soul existing at different points in time, satisfying both oneness and reincarnation.

(Not that this is something I necessarily believe, it is just something I thought about).