Well I dont think intel will have any way/tool publicly available to verify the serial numbers, however i have found this little tool-like from intel which is quite informative sometimes.http://ark.intel.com/. You can check the processor details from that tool..you can use the SL number that is on the processor to identify your processor. The FPO/batch number can be different. Then if the SL number is different then the processors are different. But also please note there are two steppings for the E5200 processor: http://processorfinder.intel.com/List.aspx?ParentRadio=All&ProcFam=0&SearchKey=e5200 but they are both the E5200 processor. So if the sl number is different from those two then i think there is something wrong with the packaging.
If you are still worried I would recommend to contact your point of purchase before going any further.