doc: Fix some whitespace issues in the man pages

doc/src/sgml/pgbench.sgml

@@ -693,8 +693,7 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
       through its standard output.
      </para>
 
-     <para>
+     <para><replaceable>argument</> can be either a text constant or a
-      <replaceable>argument</> can be either a text constant or a
       <literal>:</><replaceable>variablename</> reference to a variable of
       any types. If you want to use <replaceable>argument</> starting with
       colons, you need to add an additional colon at the beginning of

doc/src/sgml/ref/pg_dump.sgml

@@ -299,8 +299,7 @@ PostgreSQL documentation
         directory output format because this is the only output format where multiple processes
         can write their data at the same time.
        </para>
-       <para>
+       <para><application>pg_dump</> will open <replaceable class="parameter">njobs</replaceable>
-        <application>pg_dump</> will open <replaceable class="parameter">njobs</replaceable>
         + 1 connections to the database, so make sure your <xref linkend="guc-max-connections">
         setting is high enough to accommodate all connections.
        </para>