Why multiple HEAD- > master are displayed in the reflog operation of git

what does it mean to show more than one? shouldn"t there be only one HEAD?

Git
Jul.30,2021
The number in

HEAD@ {1} {} means the penultimate step, and both the penultimate step 9 and the last step take the position of the current operation back to the submission of the penultimate step 13. Back to the master branch, the number of the submitted commit is 9a9ebe0, and then the operation disappears.

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3e090-2bb5a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3e090-2bb5a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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