Update error going to 4.2.3

Update error going to 4.2.3

by Niall Sheehan -
Number of replies: 1
We are getting an error regarding a "Duplicate entry '822-29" for mdl_customcert_issues.mdl_custissu_usecus_uix' CREATE UNIQUE INDEX mdl_custissu_usecus_uix ON mdl_cistomcert_issues (userid, customcertid) Error code: ddlexecuteerror

Not sure how to resolve this issue. Please advise.
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