'Load on new tabs' means that when you open a new tab (some people open new tabs with short cuts, buttons), something is placed there, like a duplicate of the page your are on at the time, or what's new in Fx 12 - New tab page which is actually a list of previously/most visited pages. Or a blank page - that is nothing will be loaded. So it makes sense to me.
But what would you mean by 'New Tabs load on'? The only thing i can think of would be a placement, like 'on the right', 'on the left' but those settings are just below, as you can see on your shot.
English is not my native language and i might be missing something here but it makes sense to me. Unless it's not a 'proper' English.
What does not make sense to me is Current page and Duplicate page ...
unless there's a difference in retaining tab history, it sounds the same to me.
So, how do you think this option should sound if it means what i explained above? We're open for suggestions as always!
Also, since this thread has such a vast title, what are your problems? Can you try to describe it? Remember - a clean profile + last dev.version is a good start.