No, thats too much of an exaggeration.
Ignoring for the moment the word "equals" (there's no such thing when comparing CPUs), 68k and PPC do get more speed per MHz, especially compared against 486 or earlier pentiums. It's not quite 1MHz -> 2MHz, though! More like 1MHz 68K -> 1.2MHz Intel, but that's a VERY, VERY simplified example.
