OTF lists

More trouble with FontLab

[FATAL] cmap{plat=3,script=1,lang=0}: multiple glyphs uni2126 Omega mapped to code <2126>
ERROR: There was a problem while compiling OpenType font. Final .otf font is not saved. Please, check OpenType features definition for errors

Once more I am confronted with an error in FontLab, which I don’t entirely understand. Especially the help suggestion is entirely useless. I understand the issue is caused by “multiple glyphs” with the unicode 2126, but how do I find, identify and eliminate the duplicate entry if it isn’t showing up in the glyphs list? How do I know which is the right associated character, which is the original and which the duplicate?