Yeah, that's the problem I've found. I have two physical copies of Lemmings from back in the day - a pair of original disks, and a pair of cracked ones. I also have two types of disk image from the net - cracked ones in ADF format, and originals in IPF format (which also encodes the copylockedness, somehow!).
I am unable to read from the original copies (either the physical ones using the Amiga, or IPF ones using WinUAE) due to copylock.