I have a concern about two different SNP IDs being given to the same exact position: Assembly: Human - May 2004 Track: Affymetrix GeneChip Human Mapping 250K Sty Position: chr15:76,053,782-76,053,782 There are two SNPs at this location: SNP_A-4296759 and SNP_A-4294338 Is this an Affymetrix problem?