@RMSEY_007 Here is my approach when I need to delete duplicates:

Query List : Item equals Item and ID is not equals to ID
save ID in collecID
*Sort descending Created


Collection operation collecID (count) store result in countcollec

Run if countcollec not equals 0

Collection operation pop

delete record
Take a look at my wf and modify according to your needs, in my case I'm deleting an item from 2 lists and from a SQL database so ignore those actions.

Thankyou @Nunezma  !! I will implement the logic as you mentioned. 

I have implemented workflow which copies item from one list to another. 

The problem is whenever an item is updated/modified in a list A (Suppose Approved status or any custom field) it creates a duplicate entry in List B due to copy workflow. 

No I have two items in list B. 

However I found articles where they are deleting the newly created item but not deleting the exiting one - I have implemented this but recent item is only getting deleted instead of existing one. 

@RMSEY_007 ...Based on certain columns, do you want your users to enter duplicate entries or it has to be unique? Let's say you have a field for the Domain ID and if there is an item already there in the list and if the user tries to submit another for the same domain ID then it should not allow them to submit. To do so you can go into the Domain ID column settings (in list settings) and select "Enforce Unique Value" as "Yes".

Now let's say you're copying an item from List A to List B then I assume you're using Copy-Item action. If that's the case then you can check the option to overwrite an existing item.