I guess this is due to the fact you are using -H option instead of -h. -H is useful to address issues related to multiple network interface support.
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I tried it with both versions and both failed.
It must work with -h option. -H is the hostname used by the dscc registry to connect the agent. That means localhost in this case.
Did you check the status of DSCC agent on the second server? (agent which you are trying to add)
# /opt/dsee7/bin/dsccagent info
I got this answer also on a case, that I've opened!