Most of SNPs on the Y chromosome (chromosome 24) are reported as homozygous, but a small number are reported as heterozygous. Are heterozygous reports "expected," or should they be considered an error?

Likewise, for women, most SNPs on the Y chromosome (chromosome 24) are reported as 00, but a small number have reported values such as AA, GG, CC, TT, GT. Should these be considered an error?