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1.  

   Card handling

   

   Michael Kohne, Apr 5th, 2004 @ 6:22am

   
   

   I've done a little with small scale credit card systems (nothing like what Wal-Mart does, but some of the concepts are the same). There are two parts to any transaction: authorization (when you swipe the card) and then settlement (on a regular basis). What happens is that when you swipe, the shop asks the network for authorization. But the merchant doesn't get paid unless they also settle that transaction later on.
   
   This failure kind of sounds like a multiple-settle situation. At a guess I'd say that the primary system that Wal-Mart was pushing settle data into failed, and Wal-Mart's system started talking to the backup. Wal-Mart's system then re-did the settle (becuase the first one failed). Somehow both settlements then ended up in the processor's database (that's what obviously shouldn't have happened).
   
   Clearly I don't know for sure, and this is all a big fat guess (as I have nothing to do with large-scale credit card transactions like this), but hey, it's a theory anyway.

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2.  

   No Subject Given

   

   Ed Halley, Apr 5th, 2004 @ 6:50am

   
   

   Very little explanation is given .. it only effected Wal-Mart stores.

   I'm sure a few million in extra revenue that day could surely effect a Wal*Mart store, but I think you meant that the glitch affected Wal*Mart stores.

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3.  

   Re: No Subject Given

   

   Mike (profile), Apr 5th, 2004 @ 9:02am

   
   

   Who needs grammar/spell check when you've got readers to do it for you?
   
   Fixed.

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4.  

   Re: No Subject Given

   

   The Spelling Nazi's, Apr 5th, 2004 @ 11:46am

   
   

   
   
   bitter ain't she ?
   
   You would think a thank you would be in order but Mike pops off with a snide one.
   
   
   
   

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5.  

   Re: No Subject Given

   

   Mike (profile), Apr 5th, 2004 @ 12:16pm

   
   

   My comment wasn't intended to be snide at all... I was being honest in a jokey way. I guess (once again) the HTML humor tags were missed.
   
   I appreciate those who point out the spelling errors, because then I go fix them.

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6.  

   No Subject Given

   

   Anonymous Coward, Apr 5th, 2004 @ 3:22pm

   
   

   Im sure everyone's heard of the infamous, take all the partial cent's from everyone's bank account and put it in my bank account fraud.
   
   Seems to me that there have been a couple of double/triple billing problems recently... but I forget when/what the other was.
   
   Anyway, my point is that a lot of money could be made by someone if they had access to that extra money for a couple of days......

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7.  

   Re: Card handling

   

   Sean, Apr 5th, 2004 @ 3:44pm

   
   

   I also work with POS systems on a regular basis for a network provider. What I can say is the failure sounds like what is described above. There could have been a failure on the systems on the First Bank side and (failre, and then replacement systems starting from transaction #1 from wed for example). I am sure it was fun for wal-mart execs seeing the morning numbers 2-3 times higher then forcasted.

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8.  

   Re: No Subject Given

   

   Joe Baderderm, Apr 5th, 2004 @ 5:13pm

   
   

   That was from Office Space via Superman III! You shouldn't steal fractions of a cent from the children's fund!
   
   My guess is that someone was trying to earn extra miles on their card for the summer for a big trip. Or maybe somone was putting in a big bet on the Final Four. Heck, why not blame Bush or Kerry depending on your political views!

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9.  

   Re: No Subject Given

   

   Geekfather, Apr 6th, 2004 @ 8:38am

   
   

   I blame the RIAA.

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10.  

    Re: Card handling

    

    Roberto Magalhaes, Apr 18th, 2004 @ 3:30pm

    
    

    Hello,
    I am a credit card consultant. This problem is quite commmon in Brazil where I am from. All transactions, when received, are screened for several filters: valid card number, valid merchant number and so on. If the merchant accidentaly retransmits the transaction file, the credit card processor checks this file vs previous ones and detects identical transactions.
    Whenever version updates are done, programmers must be careful in validating all subroutines. My best guess is that this step was overlooked. Here in Brazil I have seen this happen many times and invariably , upon investigation, one finds the missing duplicate detection routine to be off.
    Major booboo for a large processor.

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