that situation can happened only if you do PureBoot factory reset.
there is inconsistency between Key factory reset, (can be done from GPG) , where pins will be 123456/user 123455678/admin,
and PureBoot factory reset where both pins are set to 12345678.
which is actually documented on https://docs.puri.sm/PureBoot/GettingStarted.html#oem-factory-reset
To perform an OEM Factory Reset, insert both your Librem Key and a USB disk so PureBoot can copy over the new corresponding GPG public key it generates. Then select Options → OEM Factory Reset and follow the prompts. The process will take some time as it needs to generate new GPG keys. Then once it completes you will be prompted to reboot the system. At that point you will get an alert that you will need to generate a new TOTP/HOTP secret (when prompted, the TPM admin PIN as well as the Librem Key admin PIN are “12345678”).