Outlook 2011 contacts issues

One particular user who's got almost 8k contacts complains that he cannot see all the content information of some contacts. The back end is  hosted Exchange 2010. When viewing these problematic contacts in OWA it looks like the main issue is that some information is listed as Other. The Other field doesn't seem to be showing up neither in Outlook 2011 nor on mobile devices. There is also the issue with lots of duplicates which I'm not sure how to resolve since there are so many of these contacts. So how is it possible that Outlook 2011 doesn't play nicely with OWA? How would you suggest this resolved the huge number of contacts?