Just checking the consensus on this - we currently leave them for an hour whilst we do the food shopping but for some reason, 2 hours seems different 
I need to go to town for an appointment tomorrow morning (unavoidably moved from last week) and I don't really want to take DC2 with me. DC1 is generally sensible, I would make sure I could contact them at any point and ring them at least once and in reality, chances are they would just both play on their Xboxes and not even communicate with each other whilst I am gone!
Would you do it?