Duplicate Contacts issue on Outlook.com

I am struggling with this issue since I switched from Gmail to Outlook. I exported Gmail contacts to .csv file and imported into Outlook.com account. MS Outlook 2016 (on both PC and Mac) and also on iPhone have no contacts. I wanted to sync all three device with Outlook.com server and get contacts from there. However due to unknown reasons when sync happens, I see that there are up to 9 duplicate contacts on Outlook.com contact list. Sometimes they appear as linked and sometimes separate. 

Initially I though issue is related to Sync with iPhone and MS Outlook 2016. However then I deleted all contacts from Outlook.com account and all devices and also stopped all sort of sync with iPhone, PC and iMac. Now there is no contact on any of device. Then I uploaded .csv file exported from Gmail to outlook.com account. This .csv file have 179 rows with 179 contacts. Here is what happened: I see 50 contacts appeared twice on Outlook.com People account. Rest (179-50) contacts appeared once but there are two linked contacts on each card with once exception which has 3 links. When I click on "Links" on outlook.com account, first link shows "Outlook-(contacts)" and second link shows "Outlook-(My contacts). I checked .csv file and I see last column "Categories" is filled with "My contacts" all the way. 

Next, I clicked Manage-->Clean up contacts to merge those duplicates and to my surprise many contacts are appearing up to 9 times in match list. That means somewhere inside the outlook.com contacts are listed up to 9 times.

It seems problem may be related to Outlook.com as now none of device is syncing back to Outlook.com account.

Then I tried one more thing:

I deleted all contacts from Outlook.com account and added two contact manually to Outlook.com contact list. To my surprise in few minutes, one contact was duplicated automatically. I also observed that even though I have deleted all contacts from Outlook.com (I have 0 contacts now), when I press Manage--->Clean up contacts, it shows hundreds of contacts are still there and there are lots of duplicates suggesting to merge! This is probably the root cause of issue. In spite of deleting everything from Outlook.com contacts, Contacts are retained somewhere on Outlook.com and when I add new contact, they merge and create duplicates.

On Outlook.com People page, I clicked Manage--> Restore deleted contacts. And, it showed that "you have 4539 contacts that can be restored". These are mainly same contacts which are inside .csv file I am trying to import appearing multiple times in deletion log. Is it possible that these deleted contacts residing somewhere inside Outlook.com are syncing back and merging back when I add same contacts via .csv file or manually?