Breakdown of Unique Visitors by Channel is Greater than Total

[natmcd99]

I have broken down my unique visitors (total of 56K) to view the marketing channels they came from but the numbers sum to be 59K--how would this happen as I thought unique deduplicates visitors?

[vibhatna]

@natmcd99,

In case of UVs sum of individual line items will always be equal or higher than the total because of deduplication. 

Let's say a visitor reached to the site via Paid search first and later reached to your site via Affiliate channel. In this case user is same but used 2 different channel to reach out to your site so individually both the channels will get 1 UV each but in total it will be 1 UV only. So the sum will be 2 and total will be 1.