1. A knowledge base system comprising: at least one processor; at least one storage device accessible by the at least one processor for storing a plurality of data instances; an interface device for receiving at least one data instance; and a memory storing a series of executable instructions executable by the at least one processor for capturing a received data instance and determining via a field dependent heuristic determination if the received data instance is a duplicate of any data instance of the plurality of stored data instances, wherein the received data instance and the plurality of stored data instances each include at least one field each having an item, each item including at least one token, each token including a sequence of at least one character; wherein the determination by the at least one processor comprises: for each field of the received data instance comparing between tokens of the at least one token of the field and the at least one token of a corresponding field of a respective stored data instance and generating at least one corresponding token similarity value, wherein each token comparison between a first token and a second token includes determining a degree of matching between characters of the at least one character of the first token that and the at least one character of the second token, including taking character sequence into account, and outputting a field similarity degree based on the at least one token similarity value; and for each respective stored data instance generating an instance similarity value based on the field similarity degree corresponding to the respective fields of the received data instance, wherein the determination of duplicity between the received data instance and the respective stored data instance is based on the instance similarity value.