This, I could believe, if blocks 414056 and 414072 had the same version number (since they were both made by the same pool, Slush). However, since those two blocks, made by the same pool, have different version numbers, I'm looking for an explanation. Do you think the Slush pool operator is randomly choosing what version numbers to put on the blocks it solves? I don't.
Slush runs two separate pools effectively, each connected to a different version bitcoin daemon. You choose to mine on one or the other pool. It is all done on a pool level.