Note: Please keep in mind this is my own personal theory on how Reincarnation works. If you decide to use it please cite your sources and/or ask my permission please. Thank you!
Most people would agree that a being can only have one soul at any given time in a body. I have not known this basic rule to change from all the information I've gathered from my previous lives, to the friends I know and the research I've done. I find many people often struggle to wrap their brain around the concept of Reincarnation and how it feasibly works because ultimately it takes believing in two constants that we know of, a Soul and a belief that the soul cannot be destroyed merely born anew into a new physical form. But for those who have a difficult time grasping these concepts it just doesn't seem possible in the least bit either a soul is non-existant or you die and that's it you go to Paradise or Tartarus (depending on your beliefs). No being reborn, no further learning to help the soul grow, do not pass go and collect $200.
I've come up with an analogy over the years that explains it pretty well to me and for those who are children of technology they will understand it very well (I also have an alternative explanation for those not technologically inclined).
Think of the soul as a hard-drive. With hard-drives you can parition (seperate or divide) them, however just because you parition the hard-drive doesn't make it any less your hard-drive. Ultimately it is still a part of the same whole of your Hard-drive. You can still access any and all information you store into those paritions. Our souls work very much in the same manner retaining information, experiences, etc but the physical shell (or for a computer its case/cover) changes. Keep in mind however that files can become corrupted, accidentally deleted, etc overtime (translation: memories can fade and there will be incomplete memories even that you may be able to recall but mayhaps not the full memory itself. An example is, you recall a memory but you don't remember exactly how you died. Perhaps that part was lost? Perhaps not, only time will tell along with past-life regression sessesions). Additionally, unlike Hard-drives that can eventually run out of space/memory or RAM a soul does not suffer from the same issues. As far as I can tell the only time a souls capacity for learning is unlimited.
Now for the non-tech explanation. You have a really big box! And you decide you want to get a bunch of smaller boxes filled with stuff to put into it and the reason why you are getting the little boxes is to help seperate the things you want to store in the big box from getting gumbled with everything else (much like a jewelry box) which would quite possibly ultimately lead to you getting them lost or feeling as though they are lost. The Big Box represents your soul while the smaller boxes represent those previous lives you have lived previously to this incarnation with their own personal life experiences, memories, personalities, etc all contained within these smaller boxes of the soul's memory. Unlike a regular box though the soul is more like an infinite box of space that nothing that wholy fill (except maybe being reunited with the divine spark which even that is rather debatable and I don't have a real complete answer for).
Just thought I'd share that and see what others had to add on if anything at all. Questions, comments?
"For many are called, but few are chosen" - Matthew 22:14 ver. New American Standard.
"Though my soul is born from darkness, it shall rise in perfect light, I have loved the stars too fondly, to be fearful of the night". Unknown
"On those nights that I gazed upon the full moon in longing it was always you that my heart was calling." - me