Many people (Americans, at least), use this construction (would have + Past Participle),
instead of past perfect (had + Past Participle), and with the same meaning.
If she would have studied harder, she could have gotten an A.
If she had studied harder, she could have gotten an A.
Of course, this is only in writing.
What people would actually say blurs the seeming difference between these two constructions.
Auxiliary verbs are usually contracted; in particular, would is normally contracted to a single final
- She would never do that ==> She'd never do that.
- He would answer the phone in Swedish ==> He'd answer the phone in
Would have is contracted to would've, normally pronounced /wʊdə/,
with the /v/ dropped and only the syllable remaining.
- He would have hung up ==> He would've hung up /hiwʊdəhə'ŋəp/
However, would've can also contract the would to /d/, as usual, so further contraction is possible, to
- He would've hung up ==> He'd've hung up. /hidəhə'ŋəp/
which leaves only /də/ between he and the verb. Recall that this syllable is intended to be a short form of would have, at least in the mind's ear of the speaker.
And in the example sentence, that'd be
- if she would have studied harder ==> if she'd'a studied harder
Notice that, in shortening would have successively to /də/, we have passed right through the standard contraction for the past perfect. I.e,
- if she had studied harder ==> if she'd studied harder
so the only pronunciation difference between these two forms is the presence or absence of a reduced schwa (/ə/), which can get swallowed easily in ordinary speech.
Consequently, many people don't hear any phonetic difference between these two constructions. They look very different on paper (and there isn't any semantic difference between them), but people can't tell which one others are using, so they confuse them totally, with the usual result.