On Wednesday, October 14, 2015 at 4:39:35 PM UTC-5, Jim wrote:
I'm going to put poly on them anyway, so I thought what if I used some of that shaded poly on just the light sections? Maybe just sand them again and re-try the stain?

I would not try the staining again. I'd go with toning the finish/poly. Do some sample poly toning, first, over a stained sample piece, before committing to the project. If you are to apply 2 coats of finish, your toning may need to be darkened more, than if you apply 3 or more less-toned top coats.

*The table will be in Maine. Is that too far away for convenient later applications? ....

Why do it now? The pic doesn't show the degree of difference you are speaking of, so we can't see exactly how much difference there is. Why not leave it as is, for now, if the difference isn't too terribly great. Let them live with it for a while. If, later, they decide (prefer) it should be darker, then, later, it can be darkened. It'll be (*it may be) just as easy to darken it, later, .... to apply more toned coats, later,.... as it is to darken, now.

Sonny