When there are accounts with the same name (samaccountname) in the source and target environments and you are running a migration session with the option "Never merge: skip accounts that match any accounts on Target", those accounts will not be reflected on any of the reports available at the end of the migration session.
This is the designed behavior of Migration Manager. It is matching accounts by SIDHistory and SAMAccountName as per the default settings on Object Matching tab under domain pair properties. (Matching by Email is not selected). As a result these accounts do not fall under any category of reports provided at the end of a migration session. These will not be considered conflict or failed objects.
If none of the accounts with the same account name should be merged and all such instances should be reported, please use the following approach:
On Domain Pair Properties, under Object Matching Tab, in the field 'Match Target Objects By', deselect the checkbox for "Account name". After that if you have an account pair in source and in target with the same SamAccountName, then you can see it on 'Conflict Objects' at the end of migration session.
Important: before implementing this in production take into consideration other issues this step might introduce. Those issues are described in SOL96391.
