According to the notes for the new software update for the HDS Gen-2 and HDS Touch, you will now be able so share one map chip between two networked units. If that is correct, I will have a couple month old lake-insight pro chip to sell.
• Chart-sharing – Offering both navigational and sonar enhancements, both software updates provide chart-sharing capability, which allows maps on memory cards to be shared across the Ethernet network for viewing on multiple HDS Gen2 or Gen2 Touch chartplotter displays. Insert any compatible Insight, Navionics® or Jeppesen® chart into one unit and view on any other networked HDS Gen2 or Gen2 Touch display.