+ * Adds the entry to the *normalised* list of PDBIds.
+ *
+ * If a PDBEntry is passed with the same entry.getID() string as one already
+ * in the list, or one is added that appears to be the same but has a chain ID
+ * appended, then the existing PDBEntry will be updated with the new
+ * attributes instead, unless the entries have distinct chain codes or
+ * associated structure files.