I assume that the schema is same in the source and target feature classes, if that is the case you can try to use the Append tool and see if it works.
Please see Append—Help | ArcGIS Desktop
It isn't obvious that it's GlobalID, but that error message does indicate there is a field with a unique constraint being violated by the data you are loading. In other words, check your table for unique key constrained fields and then join the two tables on that field to see if anything matches. If so, you need to pick one to delete.