Robert,
You didn't even raise the Luke passage in the first place, so (since this sort of thing doesn't much bother me) I didn't even look it up.
If the real issue for you was the difference between Mark's account and Luke's, then you should have made that clear. Harmonizing the Mark and Matthew accounts was relatively easy, the "duo" (two) term being extensible across the subsequent terms, some mss even having "staffs" (plural) possibly an early/clumsy attempt to harmonize by emendation. The main argument against NOT extending has to do with the term "sandals", a natural plural. Are we supposed to infer Jesus said DON'T wear sandals? This is contra-plausible, and inclines us to extend "duo" even before we get to "staff".
So, obviously I disagree with the NET comment that Mt.10:10 disallows taking a staff.
There's no good reason for refusing to extend; it is exactly like comparing testimony during a trial--given the context, are there reasons to understand person A's testimony as more consistent with or more contradictory to person B's? In the case of Mark and Matthew, the reasons are clearly good to understand the witnesses to be in agreement. Thus, we grant the greater probability that Matthew meant us to extend the term.
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Once you have Mark and Matthew saying virtually the same thing (and the minor variations in terminology are arguments in favor of non-collaboration or collusion), the argument for Luke's "free" rendering being a rhetorical "traveling light" comment makes even more sense (since he's the one convert-author collating multiple eye-witness testimonials, and writing at a remove of perhaps a decade or more from the events).
There is a significant problem with the inept way that modern, agenda-driven types handle the biblical witnesses. On the one hand, they claim that any apparent discrepancy (however surface or minor) amounts to a significant challenge to biblical inspiration, but mainly its truthfulness. They would not, however, demand that sort of exactitude in determining the truthfulness and accuracy of testimony of prior events, as related in a court of law.
On the other hand, if we had three witnesses wherein there was not a single variation on vignettes related by two or more, they would quite reasonably conclude that these were not independent witnesses at all. But, its almost as though they would have us believe that in that case, they would lose all their doubts and willingly accept biblical and divine authority.
Why do I find that assertion hard to swallow?