You are right, having two wrenches with 14mm and none with 13mm does not make sense at all.
This has to do with an overall change in the standardising, the so called DIN specifications (Deutsche Industrie Normen).
The standard nut size for a M8 bolt was 14mm, but, in 1965 or so this was changed to 13mm. This saves room when designing parts, and also some weight.
Anyway, before the change, there was no need for a 13mm wrench since it would not fit anywhere
Thus, this change was reflected in the contents of the Pagoda tool roll.
/Hans in Sweden
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