OK, so a) you don't want to replicate DDL, b) the system is *NOT* replicating DDL (as desired), but c) rs_helpdbrep is showing that DDL replication is enabled (Rep.DDL = Yes).
Is this correct?
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rs_helpdbrep *is* running queries against the RSSD to display info about the db repdef in question. [NOTE: There's nothing to keep you from looking at the source code for rs_helpdbrep to see where it's getting the info from.]
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As for why rs_helpdbrep is showing Rep.DDL = Yes ...
What's the full text of all 'create/alter database replication definition' commands that you submitted to the repserver? These commands are going to determine what values you see listed in the output of rs_helpdbrep.
Without seeing the actual 'create/alter database replication definition' command(s) ... I'd say someone created (or altered) your database repdef to include DDL replication, hence the reason Rep.DDL = Yes.
You should be able to run 'alter database replication definition / not replicate DDL' to disable the setting for DDL replication (ie, effectively set Rep.DDL = No).