Tattoo Tracing   The Jockey Club offers this service.   Asterisks*   Asterisks are used to indicate that a horse has been imported. Although these days the country of birth is usually shown in brackets following the horse's name, such as "Northern Dancer (Can)", in previous centuries the horse's name would have been written as " *Nearco". In early American and Colonial pedigree research knowing which horses were imported can be helpful in distinguishing between horses of the same name.   Duplicate Names   Many, many horses throughout history have had the same name. Stud book compilers faced inordinate challenges, not the least of which was sorting through numbers of similarly named horses, whilst trying to construct their pedigrees. Spot was probably the most popular name having nearly one hundred so named equines racing under it. It was common practice to name offspring after the sire or dam, even to the point that both colts and fillies would bear the same name.   Duplicate Sires   Mares are sometimes covered by more than one stallion for a variety of reasons, including the death or infertility of the first stallion. Since the stud farm presumably had reason to doubt that the mare was in foal from the first cover, the second stallion is usually assumed to be the sire. Unfortunately not all early sources listed duplicate sires in the order of covering and confusion can arise from this.   Spelling   Early spelling was fluid and no standard existed. Words appear to have been written the way they sounded to the recorder. Recorders heard things differently so sources offer a variety of spellings. For example, before approximately 1730 "chesnut" appears to have been the preferred spelling used in stud books and racing calendars, and is still used by the keepers of the General Stud Book today.