Helaman began with a band of two thousand, and has added sixty more. He now refers to them as two thousand and sixty. This appears to be a count, but does not necessary have to indicate that there was a full two thousand in the contingent (though there may well have been). Helaman may simply be noting the two separate time-origins of his force, the better to indicate that none of them were lost, either form the first two thousand or from the later sixty.