Yes, you could probably detect the overwrite through the history tables. You could look for changes in tblComputerSystemProducthist for instance.
This wouldn't help in terms of separating the machines however. A lot of tables do not have a counterpart with historical records. The only way to really solve the problem is by renaming the machines.
Report listing computers that underwent changes to the Win32_ComputerSystemProduct WMI class:
Select tblComputers.Computername, tblComputers.ComputerUnique,
tblComputers.Domain, tblComputerSystemProducthist.IdentifyingNumber,
tblComputerSystemProducthist.Name, tblComputerSystemProducthist.UUID,
tblComputerSystemProducthist.Vendor, tblComputerSystemProducthist.Version,
tblComputerSystemProducthist.Lastchanged, tblComputerSystemProducthist.Action
From tblComputers Inner Join
tblComputerSystemProducthist On tblComputers.Computername =
tblComputerSystemProducthist.Computername
Order By tblComputers.ComputerUnique