Yes I can connect(I previouly verified sysdba was granted on both nodes to dp_backup user). I will open a ticket then. Thanks for your help Bob!
NONE:10g2:ddcdb1:/opt/oracle/etc>sqlplus /nolog
SQL*Plus: Release 10.2.0.4.0 - Production on Tue Apr 1 15:10:09 2014
Copyright (c) 1982, 2007, Oracle. All Rights Reserved.
SQL> connect dp_backup/xxxxxxxx@ddcpayp1 as sysdba
Connected.
SQL>
Dave