Yes. I'm not entirely sure what that means other than I think it was re-armored by the military (perhaps after coming back from lend lease?) and they didn't match serial numbers when they put them back together.
For some reason I can't add more pictures to the post. Email me if you want more pics. I have one showing the serial number on the bottom of the receiver.
Andy
In fact, the armorers began eliminating the mismatched serial number from the lower, so there would be no confusion as to which serial number (i.e., the receiver number) was correct. That information is in Frank Iannamico's book. Therefore, the number on the lower shouldn't detract from this gun. It's very nice.
WTS: Auto Ord Bridgeport M1A1 - Price Lowered again $18,750
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Posted
In fact, the armorers began eliminating the mismatched serial number from the lower, so there would be no confusion as to which serial number (i.e., the receiver number) was correct. That information is in Frank Iannamico's book. Therefore, the number on the lower shouldn't detract from this gun. It's very nice.