eprom dumping question

I tried to dump the eproms of an old talking vending machine I have, just to have them backed up. I dumped what I thought were the contents of the two eproms, but when I compared the two dumps (from 2 different eproms), they were identical except for one byte.

Is there any reason that there would be two identical eproms, or should I try dump them again? I'm using a willem programmer 5.0e being powered from usb. Would using power from an ac adapter help dump the chips?

If anyone wants to know, the eproms are 27c010

Thanks.

edit: I tried writing my dumped file onto an eeprom, and replaced it with one of the eproms, and it still works. That leads me to believe that the dumps are good, and it does in fact have two identical eproms in it.

If I can ask this here, I've been trying to rip the audio files from the eprom dump, and I can't figure out how to. I've tried importing it as raw audio into audacity, and it comes up with some stuff, but it's just white noise.

I can't get a very good look at the circuit board because of how it's positioned, but from what I can tell, the eproms run to several different multiplexers (M74hc257), and that runs to a voice synthesis IC (m6585 http://pdf1.alldatasheet.com/datasheet-pdf/view/134889/OKI/MSM6585MAZXXX.html)

If anyone thinks they can help me rip the audio, please send me a PM

btw, this is the vending machine: http://www.arcade-history.com/pages/popup_cabinet.php?img=25694.jpg

more edit: Rather than trying to modify the original eprom file to play custom sounds, I figure I'll be better off building my own custom board. So basically disregard this thread. I've figured out what I needed.

 

Track down Kevin Horton if you can. He did some work a few years back on an early speech synthesis device, and he's a scarily smart guy all round. Might be able to give you some pointers.