Seaquel
SQL Server error code

SQL Server error 7721

SQL Server raises error 7721 at severity 16, which marks a problem with the query or data that you can correct.

Duplicate range boundary values are not allowed in partition function boundary values list. The boundary value being added is already present at ordinal %d of the boundary value list.
Msg7721
Severity16
Group7000–7999

Source: Database Engine events and errors