Tried to read through the blog post, but couldn't get past the declarations about how many people any one soul can hook up with. Maybe I misunderstood it (I re-read it but still didn't quite get your meaning).
In my case, I believe I have a soul mate hubby, Danny, and a twin flame BF, Michael. My soul mate and I are very different, and I've grown a great deal during our time together. Michael is almost exactly like me in every way, and we work very well together. He challenges me by displaying my own shortcomings in my face.
I don't know how this works with others, but Michael is very loyal and non-poly. (Is this a common trait of twin flames?) He would never look outside our relationship for more. Danny can, and has, although he's committed to me. As for me, I'm happy with both and not looking, but I'm not of the opinion that I'll drop dead and/or stop having sex if either of them leave.
Anyway, interesting topic!