Well that's always a possibility but in this case I don't think so.
It's a genuine holographic Windows XP version 2002 disc (with product key) and upon which it clearly states 'Includes Service Pack 3' and that is what has been installed and it has passed Microsoft's verification process. When I open up Properties in 'My Computer' it plainly says 'Windows XP Professional Version 2002 Service Pack 3' on the General tab.
My understanding was that the SPs are cumulative. If you have SP3 then you automatically have 1 and 2?