I doubt it should be renamed: Hibernate does not know that it is the same constraint that it generated earlier in another deployment. You will have to do that manually.
But Hibernate should create an unique constraint with that name, if none is existent ON TABLE GENERATION. Indeed it seems to be a bug in Hibernate 4.0.1 (which creates the constraint with the name of the first column only on new table schema generation) which is solved in 4.3.0 (which creates the constraint with the correct name, even if the table already exists).