I think I tend to loosely commit to an exclusive relationship until it either goes full-on or full-off, so I can understand the mindset of a Dual who wants to keep her options open.
This is not an ideal approach to relationships, though, and it would seriously worry me if it weren’t for the fact that I was in a fully-committed relationship (at least, from my perspective) for many years.
I did it once, I can do it again with the right person.