I don't know how those extra scripts got there exactly, but they were removed for 2.50.3. I think those were entirely from qst.dat and weren't actually saved with the individual quests, since they're written in a for(int i=0; i<NUMSCRIPTGLOBAL; i++) loop. Loading an older quest in the current build, I don't see them.

I wouldn't expect them to cause a crash, though, since global scripts are loaded into the array in a similarly limited loop.