TIG, it all about his odd input field, that takes spacings.
It is not two objects spaced 10m apart, it is 2 objects spaced at 5m intervals, from a common start point that might also have a 1st object. (Think fence posts, here.)
But then using the "odd" input defeats the automatic unit conversion of the inputboxs.
At this point @vanlion, I'd suggest switching to a list of spacings like:
It's just too strange for the user interface with those embedded (x) multipliers.