As content manager I am using linked sheets to give my document owners the
fields to enter their chosen meta data. they all use different excel files to
update a SharePoint list.

They complain that the SharePoint doubles some of the lines they create,
looking in the SharePoint list 'time of creation' field - I can see that the
lines were entered by the same user at different times, which are not work
time hours.
Is it possible that the link doubles the lines?!

I also have a problem that the excel list sometimes will not synchronize
with the SharePoint unless all changes are discarded. I think it's happening
after the users say 'no' when excel prompt them to synchronize (he notice
that there are changes in the list that were not synchronized).

any advise about that?