MSSQL - Fix Error Column names in each table must be unique. Column name 'col1' in table 'TableTest' is specified more than once.

Msg 2705, Level 16, State 4, Line 1
Column names in each table must be unique. Column name 'col1' in table 'TableTest' is specified more than once.

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to fix it replcae

ALTER TABLE TableTest
Add col1 int
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with

ALTER TABLE TableTest
Add col1UNIQUE int
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