On my websites, I define a "variety" as a unique combination of date, obverse and reverse design, and include any inadvertent man-made changes such as repairs or variations in date width as "sub-varieties". Michael Gouby has made an attempt to record all the various date widths in his book "The Victorian Bronze Penny". He does not record any variations in 1864 date width but these date variations are so commonplace in bronze pennies that it would be virtually impossible to document them all.