I always thought "wreck and ruin" was a malapropism.

The interesting thing is that wrack and ruin is a set phrase, and I'm not sure that wreck and ruin is not synonymous. Many object to rack and ruin, under the impression that rack as a noun means a instrument of torture or something to hang one's hat on, but, as I said in my reply to tsuwm's explanation, wreck and ruin have been being used for at least a century and a half. What if I wanted to use the compound kith and sib (or the punning kith and cousin) rather than irreversible binomial kith and kin (i.e., friend and relative)? Would that be incorrect or a malapropism? Wreck and ruin is not quite the same thing as using wreck for wreak as in havoc.

Ceci n'est pas un seing.