Combining Data Sets without Data Duplications

[ShrimpCreole]

I have two data sets Old and New which I wish to combine.  There is date overlap.   How is the best way to put these two together without data duplication where the dates overlap?  I am not sure whether to merge or append but, most importantly, do not want duplicaton.   

[Greg_Deckler · Accepted solution]

@ShrimpCreole Append and then remove duplicates in Power Query.

[ShrimpCreole]

Greg, is there a way to automate the removal in power query?   The NEW set pulls a rolling 26 months, so the overlap will change daily, if refreshed daily.