I recently deleted a course off my testing environment, but now when i try restore a course i keep getting the below message?

Error writing to database

More information about this error

Debug info: Duplicate entry '3087-173' for key 'mdl_courcomp_usecou_uix'
INSERT INTO mdl_course_completions (userid,course,timeenrolled,timestarted,timecompleted,reaggregate) VALUES(?,?,?,?,?,?)
[array (
0 => '3087',
1 => 173,
2 => 1405591460,
3 => '0',
4 => NULL,
5 => '1405591510',
)]
Error code: dmlwriteexception
Stack trace:
line 446 of /lib/dml/moodle_database.php: dml_write_exception thrown
line 1098 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 1144 of /lib/dml/mysqli_native_moodle_database.php: call to mysqli_native_moodle_database->insert_record_raw()
line 2504 of /backup/moodle2/restore_stepslib.php: call to mysqli_native_moodle_database->insert_record()
line 137 of /backup/util/plan/restore_structure_step.class.php: call to restore_course_completion_structure_step->process_course_completions()
line 103 of /backup/util/helper/restore_structure_parser_processor.class.php: call to restore_structure_step->process()
line 151 of /backup/util/xml/parser/processors/grouped_parser_processor.class.php: call to restore_structure_parser_processor->dispatch_chunk()
line 91 of /backup/util/helper/restore_structure_parser_processor.class.php: call to grouped_parser_processor->postprocess_chunk()
line 148 of /backup/util/xml/parser/processors/simplified_parser_processor.class.php: call to restore_structure_parser_processor->postprocess_chunk()
line 92 of /backup/util/xml/parser/processors/progressive_parser_processor.class.php: call to simplified_parser_processor->process_chunk()
line 190 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser_processor->receive_chunk()
line 278 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser->publish()
line ? of unknownfile: call to progressive_parser->end_tag()
line 179 of /backup/util/xml/parser/progressive_parser.class.php: call to xml_parse()
line 158 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser->parse()
line 110 of /backup/util/plan/restore_structure_step.class.php: call to progressive_parser->process()
line 181 of /backup/util/plan/base_task.class.php: call to restore_structure_step->execute()
line 177 of /backup/util/plan/base_plan.class.php: call to base_task->execute()
line 167 of /backup/util/plan/restore_plan.class.php: call to base_plan->execute()
line 333 of /backup/controller/restore_controller.class.php: call to restore_plan->execute()
line 184 of /backup/util/ui/restore_ui.class.php: call to restore_controller->execute_plan()
line 107 of /backup/restore.php: call to restore_ui->execute()