Hey @jesseb
Klaviyo integrates with mailchimp and you can pull in data directly in klaviyo, however if you want to do this manually, you need to export your audience from mailchimp with all the data attached to their profile, like, Name, Email, address, Open email, Click email etc and then upload it manually to a list in Klaviyo. please note that - while doing so, Klaviyo will ask if those profiles have given consent to email marketing or not, so it is always advisable to upload profiles who have given email marketing consent
in klaviyo - it will only create one profile per email, so there wont be any duplicates.
when you say email blast, then i think you mean sending an email campaign - so yes, if you send it again to profiles, they will get the duplicates, so what you do instead is send the email blast (campaign) to a segment with definition -
is or is not in the list - is in list - ‘New list that you imported’
AND
‘received email zero times over all time where campaign name equals *previous email that you sent out*
and now you send to this segment and profiles wont receive this again if they already received your email.
For the automated flow - just clone your existing flow and change the triggered list to the new list you imported and this will just be another flow you will be sending your emails from
if you want to keep the list the same, they wont go through the flow again as in klaviyo - profile can only enter a list or segment triggered flow once (so you are good on this end as well)
I hope this helps and thank you for sharing your question here in the community.
Cheers
Arpit