Villagers contains same trade with differents price

All villagers contains the trade with Rotten Flesh and then Gold to exchange one Emerald but the first one exchange 29 Roten Flesh versus 1 Emerald and the second one 27 Rotten Flesh versus 1 Emerald.

I have tested this bug in 5 differents villages and ALL villagers have this bug !

Thanks for correct this bug and for the reading.