-- first table
SELECT DISTINCT IDENTITY(INT,1,1) as ID, ComputerName INTO ComputerInfoTable FROM MasterTable;
-- second table
SELECT
a.Id,b.Id AS ComputerId,a.Vuln,a.ScanDate
INTO VulnerabilitiesTable
FROM
MasterTable a
INNER JOIN ComputerInfoTable b ON a.ComputerName = b.computername;