This tool produces fields of data type Double, so only input fields of type Double can be overwritten by the tool. The input fields identified in the message are not of type Double, so for these fields, new output fields were created instead. The new output fields have the same name as the input fields along with an underscore and index number.
No action is required.
To allow overwriting of fields, the Calculate Field tool can be used to create Double fields from other numeric fields. These fields can then be overwritten by this tool.