Azure users sync question

Question

Hi, i would like to set up user / group sync via Azure application but wanted to ask about existing users. Will they be duplicated or merged if they already exist. 
 It seems that there may have been some sync via Active directory quite a while back but there are users that left years ago still listed so will these be removed once the sync is set up or will it need to be removed manually? 
 I have no problem running some housekeeping on the users/groups once done, just wanted to know the consequences of the new directory services been added. 
 Hope that makes sense!! 
 Lee

RichardP · Answer

In general, we don't delete things. 
 So, I would remove the users you are sure are gone. 
 As for sync and matching to existing objects - we do try do that but we are conservative in the matching and will err towards creating a new object. Basically, if we can find that it is the exact same object (it was synced from the same Azure AD and it matches exactly in data) it will link in. This is to prevent creating scores of duplicates on each sync. However, there seems to be some ambiguity in your scenario - so I can't tell you exactly what will happen. 
 My suggestion would be to clean the Central Dashboard users to the ones you know are valid and then do the sync to link in the Azure AD data.