I've found that the "rules" about naming children are really common customs that are used sometimes, but not always.  In addition to sons having the same name as a living relative, I've found that half brothers (same father, different mother) have the same names.  I haven't tracked down all the details yet, but it has happened often enough that I consider the Askenazi naming custom as just part of the evidence to be considered, not the final decision when evaluating the evidence.

Peggy Mosinger Freedman
Atlanta, GA