A certain MiNE 109, of uk.rec.audio "fame", writes :

Refer to my earlier comment about how easy and common it is. You'd have
to really, really, really, really want to do it.

It is easy and common now, but of course LPs now only account for a tiny
part of the market.

It was not easy or common at the time when LPs were popular - let's be
really generous and pick 1990 as a cut-off date. Certainly in 1990
digital audio workstations and editing by computer were still a thing of
the future.

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"Jokes mentioning ducks were considered particularly funny." - cnn.com