Yes, you are correct, for double shear the error makes no difference. For single shear however, that quotient is off by a factor of 2. I scanned the Huth paper and it is 22GB.
Regarding the Huth calculation for spring constants for mechanically fastened joints, there is an error in Huth's equations printed in ASTM STP 927 (1985) which is what everyone seems to be using.
The second to last quotient reads: 1/(n*t1*E3) The n should be replaced by a 2 and read...