Creating Duplicate Table in SQL SERVER 2014
Explicitly named constraints must be uniquely named within a database.

If they are not unique, you'll see errors like this:


  Msg 2714, Level 16, State 5, Line 10
  There is already an object named 'PK_SomeTable' in the database.
  Msg 1750, Level 16, State 0, Line 10
  Could not create constraint. See previous errors.  


This is especially pertinent for creating #temp tables.  Never specify the name of a constraint when creating a #temp table, since concurrent executions of the code will fail with the above error.

Take for example:

CREATE TABLE dbo.SomeTable
(
    ID int NOT NULL
        CONSTRAINT PK_SomeTable
        PRIMARY KEY CLUSTERED
);

CREATE TABLE dbo.SomeTable2
(
    ID int NOT NULL
        CONSTRAINT PK_SomeTable
        PRIMARY KEY CLUSTERED
);


The command fails because PK_SomeTable is defined twice, once in each table.  However, if we re-code the 2nd statement:

CREATE TABLE dbo.SomeTable2
(
    ID int NOT NULL
        CONSTRAINT PK_SomeTable2
        PRIMARY KEY CLUSTERED
);


Now, it works.

For #temp tables, you'd use the following construct:

CREATE TABLE #SomeTable
(
    ID int NOT NULL
        PRIMARY KEY CLUSTERED
);