Liz, I am not sure what the numbers refer to in the lot numbers you have to work with (for example, does the 71 in 71.31.3 refer to the year 1971? what does the 31 refer to? etc) but if you want to keep these objects grouped under these same numbers (probably wise to do, rather than renumber) you could tack a letter onto the end for the individual items. For example, 71.31.3 would be 71.31.3a and 71.31.3b because there are two objects in the lot. This way you can make each object an individual record in PastPerfect, but still keep the old number for reference purposes.