I'm 100% confused by the chapter numbering, afraid to post spoilers and totally not understanding how both versions can be handled as one thing instead of separately (including within the Tankobon, not just here), so all I'll say is: it's a pretty good series so far! Funny, cute and relatively unique.

I suppose they could just be bundling them together just for the purpose of having them collected in a single book series for sale purposes?

The serialization is just so much different/better I can't imagine them being connected.