@Velius:
Ist leider nicht ganz richtig, denn die eigentlichen Rechner-SID (Local Workstation SID) wird nicht geändert, lediglich die User-SID wird für die Anmeldung und das relevante Security Token und die Trust Relationships verwendet.
Auszug aus http://www.microsoft.com/technet/archive/ntwrkstn/deploy/depopt/cloning.mspx
Note: If two workstations have the same primary SID and are participating in workgroup/local authentication security, the first user account generated (and so forth) on each workstation is the same because the SID on both computers is the same. See "Consequences of Duplicate SIDs in a Workgroup Environment" for an example. More information: MS TechNet : 162001
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Consequences of duplicate SIDs in a workgroup environment
If a company has 500 cloned desktop computers—all with the same SID—running in a workgroup/peer-to-peer model, significant security challenges arise. Each workstation would have no way of differentiating a local account from a remote account. Restrictive access to secured files and directories through SID certification would be impossible, and tokens being used would all contain the same SID. The entire security structure based on SIDs and access tokens would be compromised. For more information see MS TechNet : 163846
Example:
\\WS1 and \\WS2 are two workstations at Netwerks Corporation. Deployed using a binary disk image–copying program, these workstations have duplicate security identifiers.
Eric on \\WS1 has a local machine account on WS1 of S-1-5-21-191058668-193157475-1542849698-1000.
Stephanie on \\WS1 has a local machine account on WS2 of S-1-5-21-191058668-193157475-1542849698-1000.
Eric is performing employee performance reviews and saving his information to C:\Data\Reviews on his local NTFS drive. He uses Windows NT Explorer to share the directory and to set the security rights so that he is the owner and only he has rights to access the files.
Stephanie is logged onto \\WS2 and is browsing the network using Network Neighborhood. She recognizes \\WS1 as Eric's machine and attempts to connect to a Reviews share that Eric created. She is given complete control over the contents because her SID (S-1-5-21-191058668-193157475-1542849698-1000) is identical to Eric's (S-1-5-21-191058668-193157475-1542849698-1000). As one can see, there is no way to differentiate WS1\Eric from WS2\Stephanie because the SIDs are identical.
Taking this to the next logical step, any data stored on removable media that are formatted using a secure NTFS scheme is no longer secure. Because duplicate SIDs exist, there is no way to completely secure sensitive data in an environment of binary duplicated machines that share an identical SID.
Consequences of duplicate SIDs in a domain environment
If you had the same 500 disk-imaged desktop computers running in a domain model, all with the same SID, the impact is significantly lessened. All users are logging into a domain and are being assigned a domain-based user SID. This SID is, by nature of the domain model, guaranteed to be unique and can be used to secure files and resources within the network. The Security Account Manager has no problems distinguishing users because they are coming from a common, centralized domain security database and all processes and tokens are running within each user's security context. Note You will still have local security issues when dealing with local machine accounts (administrator, guest, etc.) as outlined above.
Greetz
Gulp