It seems that Powerdrill add another set of mergevars to the first existing instance of an email in a message, if I try to add another recipient with the same email. Maybe desired behaviour should be to output a warning, and ignore the merge_vars from the message.to with the duplicated email.
At this point Mandrill can't handle an array of recipients where there are duplicated email: http://stackoverflow.com/questions/28047805/mandrill-personalized-message-to-recipients-with-same-email
It seems that Powerdrill add another set of mergevars to the first existing instance of an email in a message, if I try to add another recipient with the same email. Maybe desired behaviour should be to output a warning, and ignore the
merge_varsfrom themessage.towith the duplicated email.