Two iMacs - 1 Serial Number, What's Up?

Question

Hi all,
It's computer invintory time again here at school, and I've got a rather unique problem. In a lab of about 25 G3 iMacs, two of them share (almost) the same serial number when reported by the Apple System Profiler.
I don't have the serials handy with me, but I can get them if need be.
Computer #1 is a 400MHz slot loading Lime iMac, the serial number on the case matches the serial number reported by the Apple System Profiler. ie: 1234567890
Computer #2 is a 333MHz tray loading iMac, the serial reported by the Apple System Profiler is 1234567-890, and the serial on the case is totally different. (ie: 6231532140)
The only difference according to the ASP the '-'.
1234567890
1234567-890
The logic board for 400MHz computer has not been switched, but the RAM and hard drive have been upgraded. I'm unsure if the logic board on the 333MHz iMac was switched, but I wouldn't be surprised if it had been.
I've tried new System Folders, ran ASP off a bootable CD, reset the PRAM and NVRAM, trash the ASP prefs and I've gotten the same result every time.
Both computers have the most up-to-date firmware, and are running OS 9.2.2.
Anybody ever heard or seen anything like this?

Answer 1

Daniel_R....
I am with Duane as not to trust ASP with the Serial Number issue, however I disagree with it being flashed into the motherboard on CRT models.
I recall that the iMac (CRT) models contained their SN from within the HD. I ditched my petty 6GB HD too soon to see if either a reformat or a zero all data could erase it, however the SN was lost right away with a new HD months after purchase. The iMac G4 (FP) models was the start of having the SN made into some part on the motherboard. I cannot answer other than my eMac as to what other models have motherboard based SNs but I would guess Jan-2002 Mac models and thereafter.
...Ron