if it works in MAME it should work on real h/w. Maybe re-read/re-verify your ROM has the same data. When reading use CRC32 to check it. Most EPROM programmers just give a byte checksum which is not good enough if the ROM isn't reading 100% right every time. If your software has the option make it give you the CRC32 after reading it. I've had plenty of suspect ROMs read the same byte checksum on multiple reads but the CRC32 was different each time. Otherwise if it works just accept it as-is and be happy you got a free upgrade. If you had bought it from Midway it would have cost several hundred dollars