The only time one hub engaged is likely to cause a problem is if you think both are engaged, and engage four wheel drive while moving, which, apart from being noisy, is not very kind to the transfercase. In other words, it is a non-issue.
I have free wheel hubs on my 2a, but I did not pay much for them. In my view, the only advantage is they allow easier manoeuvring on hard surfaces in low range, for example, hooking up a trailer, plus they allow me to operate at high speed on the highway when I have suspect U-joints on the front prop shaft! Normally, they are locked.
John

