I had this problem also and resolved it, but still have unanswered questions. I had the problem on an iPad updated to iOS 13.1 (or the iPad equiv) and on a iPhone 11 Pro Max on iOS 13. When syncing contacts via iTunes, I got duplicates, sometimes triplecates, and contacts from old e-mails. Question: where does iTunes app in Windows 10 (most recent release) sync contacts??? It is not the Windows Contacts folder which does not seem to be used any more. It is not the "People App" which can copy an Outlook.com contacts list. It is not Outlook.com contact list if you set it as such (I had no duplicates there). I tried in iTunes both "Windows Contacts" and "Outlook Contacts" and both of them are screwed up. I check my iCloud and don't have contacts there. I check other iPhone accounts and none of them are syncing contacts. I could not figure out where iTunes was getting the contact list from and neither could an Apple Support guy that I had a call with.
Answer: I turned off the iTunes sync contacts option. I toggled my iPhone Outlook.com contacts switch to delete all contacts from my phone. I needed to upgrade to iOS 13.1. Then with the iPhone set to sync the account Outlook.com, I was able to get the correct contact list on my iPad and iPhone.
Never had this problem in previous releases. In fact, my iPad was syncing contacts fine before I upgraded to iOS 13.1. Then when I upgraded, it was screwed up. Something is definitely broken with the iOS 13.x iTunes contacts sync.
