A method of quantifying multiple target nucleic acid sequences in a sample includes generating from a sample at least a plurality of first template molecules and at least a plurality of second template molecules. At least part of said first and at least part of said second template molecules are randomly distributed into individual reaction sites. A cluster of nucleic acid amplicons of said first template molecule and at least a cluster of nucleic acid amplicons of said second template molecule are generated by clonal amplification or replication. The ID codes of all said nucleic acid amplicon clusters are identified. The quantity of at least said first and second target nucleic acid sequences in said sample is quantified by statistical analysis of respective positive numbers of identified unique ID codes of first and second target nucleic acid sequences.