[galaxy-user] fastqc and blast?

Hello mates, I have two doubts galaxy: a) I have rna-seq data from Illumina and do fastqc ... the results are good but when I fastgroomer to Sanger format and then fastqc ... the results are bad. Does anyone know the cause? I do not understand why. b) With the same sequences can know if they are different Rna and eliminate those that do not want to examine? merry christmas :)