SQL Server 2014 :: Error On Unique Index - Duplicate Key When Insert / Select

I have an issue where I am getting an error on an unique index.

I know why I am getting the error but not sure how to get around it.

The query does a check on whether a unique value exists in the Insert/Select. If I run it one record at a time (SELECT TOP 1...) it works fine and just won't update it if the record exists.

But if I do it in a batch, I get the error. I assume this is because it does the checking on the file before records are written out and then writes out the records one at a time from a temporary table.

It thinks all the records are unique because it compares the records one at a time to the original table (where there would be no duplicates). But it doesn't check the records against each other. Then when it actually writes out the record, the duplicate is there.

How do I do a batch where the Insert/Select would write out the records without the duplicates as it does when I do it one record at a time.

CREATE TABLE #TestTable
(
Name varchar(50),
Email varchar (40)
)
Insert #TestTable (Name,Email) Values('Tom', 'tom@aol.com')

[Code] .....