I used the arcGIS tool feature class to feature class to successfull merge two identical feature classes [one with partial data and the other resting on a database connection]. However when I attempt to do this with arcPY I get a ERROR 000258: layer already exists, failed to execute .
The call looks like this
arcpy.FeatureClassToFeatureClass_conversion("roads", C:\fullPathTo.sde, "roads")
Other enviromental varibles have been set accordingly, but I am looking for what the GUI tool does in this situation, an automatic merge, taking the left [local] data and meging it into the .sde.