Миграция Ларавела Удалите уникальное ограничение
/** To drop an index you must specify the index's name.
Laravel assigns a reasonable name to the indexes by default.
Simply concatenate the table name, the names of the column in the index,
and the index type **/
// Format of unique key tableName_column_unique
$table->dropUnique('users_email_unique');
Smiling Starling