Set 1:                         Set 2:
           AAAAA                          AAAAA
           ATCGA                          AACGA
           ATAAA                          ATAAA
                                          ATAAA
Consensus: ATAAA             Consensus:  A[AT]AAA

Note: like Set 2, there can be other cases that has
more than two consensus in a particular position.
They need to be captured within square bracket [].