Umm... If there is no functional purpose for the duplicate provincial campaign, you might as well remove it.
If you don't plan on including any provincial campaigns, you can remove the Provincial Campaign choice from the menu. Edit PI\data\menu\Rome.lnt, search for <lpage>new_game and remove this xml block:
Code:
<UI piece>new_game_provincial_campaign
<identifier>UIP_PROVINICIAL_CAMPAIGN</identifier>
<Parameters>
<x>256</x>
<y>383</y>
<width>512</width>
<height>38</height>
<menu_id>provincial_campaign</menu_id>
<UI text>UI_NEW_GAME_PROVINCIAL_CAMPAIGN
<font_id>arial_split_CAF</font_id>
<align>centre</align>
</UI text>
<tool_tip_id>UI_NEW_GAME_PROVINCIAL_CAMPAIGN_INFO</tool_tip_id>
</Parameters>
<object_id>empty_push_button</object_id>
</UI piece>