I just tried exporting a lemma file from Concordance and noticed a strange thing:
commas between word forms seem to be shifted one position to the left, like this (please don't mind the Cyrillics):
АВТОСАМОСВАЛ -> ,АВТОСАМОСВАЛААВТОСАМОСВАЛОВ
уступ -> ,УСТУПАУСТУПОВ
when it should be:
АВТОСАМОСВАЛ -> АВТОСАМОСВАЛА,АВТОСАМОСВАЛОВ
уступ -> УСТУПА,УСТУПОВ
The entire lemma file is attached for context.
I wonder if you could give this issue a look some time in the future (not urgent by any means).