You are seeing undesirable merges.
You want to know what "No Match" refers to in the Merged Resources report (Reports > All Reports > Notification Server Management > Server > Resource Reports > Merged Resources).
ITMS 8.x
Resources are merged if they have the same merge key with the same value.
The source of "No Match" entries happens when a forced resource merge takes place, not by resource keys.
In this particular case, the merge is triggered by Asset scheduled task - 'Run Duplicate Computer Merge on Schedule'. The merge source is Altiris.AssetContractCommon.ExecuteDuplicateResourceMerge method.
The situation when the key field in the report contains the value "No Match" occurs when the resources were merged by another field (not by resource keys).
The logs show that the "Duplicate Computer Merge" task was launched.
This task automatically merges the computers that have identical System Number, Serial Number, or Barcode in the Configuration Management Database (CMDB).
When you use the Duplicate Computer Merge task to merge computers, the following restrictions apply:
You cannot merge two unmanaged computers.
The log shows that the computers were merged.
To avoid merging, both computers must be managed, then they will be skipped, or customers need to use additional task settings and add Ignore value or/and Exclude filter.