TMGR: Can't Use a Field More Than Once

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To determine which fields are currently in your table and which fields are available for use, click Add/Remove Columns on the Format menu. In the Add/Remove Columns dialog box, under Show These Fields, is a list of all fields that are currently in your table. Under Available Fields are the fields that are still available to add to your table.

The only way to mimic having the same field duplicated in your table is to add a custom field and copy the contents of the original field to the new custom field.