You should be able to merge Inventory / Assets if there are duplicate records. That way information is not lost and then you can choose which fields to keep on both records and / or which is the primary to merge from and to.
There should also be a page that alerts you that there are potential duplicates that have similar records (e.g. the same serial number or asset tag), that way records are kept up-to-date and only one record is every discovered and updated when there is any sort of Discovery Probe or Asset Integration installed. You should then be able to mark it as not a duplicate or merge it from this location.
It should also scan and update the records in all the sub-categories not just import or move them all to computer or mobile. This is silly and could cause duplicate records on its own.