@3xzet
If a client has a mod installed then it causes a mismatch, if they are simply jumping between servers and don't have it installed then yes, you are right it will just download the different version into the cache.
As for the naming conventions it is simply an idea, you don't have to use it. Although I should mention each package for a mods assets needs a unique name, ie can't have texture and animations both named "MyWeapon", suffixes are pretty much a must.
And true, he didn't probably didn't know about the zed but if Hemi had named his 'MobBastard' or 'MIBastard' and the other guy 'WeapBastard' or simply 'BastardSword' then there would have been no problems at all.
I can't make you use, or even care about, a naming convention or potential mismatches for that matter, it's just simply an idea in light of a lot of mismatches I've been hearing about in the community. Not just the few posts around here. (Which is to many IMHO)
*Edit*
Oh, and a classic example of this would be my Colt Python that has been edited heavily on the killingfloor.ru boards. Not one person renamed the packages (that I could tell, I can't read Russian and I swear Google takes the piss when translating) So anyone that had installed those files that tried to join a server running my version would have problems.