'extra' alleles

Spartanburg Co., SC Berry John Berry, #126, received his Y-DNA13-25 marker panel yesterday, completing his Y-DNA37 order.

No particular surprises as far as the Spartanburg Co., SC Berry family is concerned but individually, John has extra alleles at DYS# 464 and DYS# CDY a/b.    John has DYS# 464 values of 15,15,15,15,16,17 and DYS# CDY a/b values of 39,40,40.

Interesting  -  but also confusing and puzzling.

If anyone understands the significance or ramifications of these results I'd appreciate your help.

Catherine, at FTDNA, explains, "Multiple Alleles can be helpful in confirming recently related individuals (two men with the same surname and with multiple alleles who match each other, and other males with the same surname, but who do not have multiple alleles, are more recently related to each other than to the others with the same surname and same marker values who do not have the multiple allele values)."