counterfactual conditionals

[P2052 at AOL.COM]

Otentimes, "The "would have" of conditional clauses gets reduced to "would
of" and even, "woulda".   I guess that "If . . . would have,  . . . would
have," is analogous with the prescriptivist grammarian's logic about double
negatives:  two negatives make a positive.  Nonetheless, superimposing one
hypothetical marker, "if," over another, "would have" (counterfactual)  is,
at the least, redundant.

This discussion reminds me of how surprised my students are to discover that
they can say/write "had had"  (If I had had enough time, I would have stopped
by the mall.")   They usually say or write, "If I would have (would of /
wouldda) / hadda) had. . . . "    Over the years, only one or two have
admitted to to ever having been formally taught this pattern.
                PAT