Bot,
You may very well be correct, but ßGød's line does pretty much guarantee that only blocks for RC5 will be crunched.
I guess it's kinda like some of the old command line switches I still use from DOS 5.0 days, like the /s /e on xcopy(in later versions only /e was needed), but I still put them both in out of habit from doing it so much; when I was doing RC5, I used the same syntax as what ßGød gave.