I thought you guys were talking about other parties that are more rivals or for role playing, rather than opponents.
Yes, in the last adventure, the PC's faced off against something resembling a party -- a group of mercenaries with humanoid subcontractors -- but I thought of that as interesting monsters (stuff meant to be killed within a single adventure), not so much a party.
As for the rival adventurings bands seeking a treasure, I did that too, long ago, when running the Lost Caverns of Tsojcanth. I believe the intro mentions that rival countries are interested in Daoud's Wondrous Lanthorn, the near-artifact in that adventure.