Adobe Marketo Engagement Program Tip
Engagement programs are intelligent enough to only send email assets in the stream 1x to a person and it would skip sending the email again if it has already been sent to the person earlier.
A lot of Marketo users have a misconception that this only applies if the email was sent out from the same engagement program earlier, but that's not quite the case here.
In reality, the engagement program would skip sending the email asset if it had already been sent to a person from any campaign/flow/program. One more thing to note here is that the engagement program looks for email assets in the activity log by their unique asset id and not by their name.
Due to this behavior of the engagement program, it is always advisable to think twice and be wary of the potential repercussions before referencing the same asset across multiple Marketo engagement programs/campaigns.