From the WP-o-Matic help:
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How it works
To avoid incoherent dates due to lousy setup feeds, WP-o-Matic will use the feed date only if these conditions are met:
First, of course, if the option is enabled in the campaign settings
->> The feed item date is not is not too far in the past (specifically, as much time as the campaign frequency)
The feed item date is not in the future
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The problem is that I am importing a feed with old post dates, so how can I make it keep the original dates? Maybe a simple hack on the code?