Originally Posted by 3 Putt Again
OK, if there is not a problem with A having more than 14 clubs unless he uses one of B's clubs, lets go back to the original question. Is there anything that would prevent A from helping B by carrying his clubs? If so, is he considered to be B's caddie? As you earlier indicated, there are a bunch of issues if he is a caddie. The Rule 8 issues can be consciously avoided but issues that could come up under rules 18 & 19 are more troubling. For example, I foresee A, with both bags on his shoulders, accidentally kicking B's ball that is lying in the rough.
In a practical sense, your caddie can not be a competitor. Otherwise some of the rules of golf can not be properly applied. Example: See definition of "outside agency", which is then used in some of the rules you cited.
I see two possibilities, the competitor would not be considered your caddie, or he would and you would then be in no mans land. I'm thinking that although the rules define a caddie as someone who carries your clubs, the inability to apply the rules of golf trump this, preventing the competitor from being judged a caddie. Another possibility I guess is a DQ, but I'm not sure under what rule.
It's a interesting question, I'll see if the USGA wants to answer this one.