to drop the key or not to drop the key

that is the question:
when doing a walk cycle with stride length, I’ve been doing the two Identical extremes at 0 and 40, then doing the cycle in the NLA from 1 to 40, thus dropping one of two identical frames.
Is this right? Or is the NLA assuming that the first and last frames are identical and dropping/overlapping them for me?
I’ve also been ‘bracketing’ my cycles- copying the second pose and placing it after the last and the second to last before the first.
The actual action keys now go from -5 to 45, and I use 1 to 40 in the NLA. Any thoughts on this?
PS reason I’m bracketing is to get the interpolation of velocities looking the same coming in and out of the action.
:o