You could create this procedure in another schema.
You are not able to create another procedure with the same schema, name, and a number of parameters.
If you think you did it, please, provide the output of the following select statement with a schema and a name of your procedure.
select ROUTINESCHEMA, ROUTINENAME, ROUTINEMODULENAME, SPECIFICNAME, PARM_COUNT
and routineschema='...' and routinename='...'
The problem description is incomplete because it does not specify whether the PROCSCHEMA was unique for the dup specificnames & signatures.
In DB2 LUW the specificname has to be unique within the procschema.