The only thing I am aware of on the market is this little guy from MiniBox.com
http://www.mini-box.com/Y-PWR-Hot-Swap-Load-Sharing-Controller
This unit will accept inputs of 5-30V and will sum two AC-DC adapters at up to 10A per channel (15A peak) with a total maximum output of 20A. As an example you could use two HDPlex 160W AC-DC units (19V, 8.4A) and sum them to produce a single 320W line (19V, 16.8A) to power a Dynamo Mini/360 Combo or HDPlex 400W DC-ATX. If you had a pair of 24V Meanwell EPP 200-24 units (24V, 8.3A), you could use this unit to provide a combined power supply of 400W (24V, 16.6A) which would also be compatible with both the Dynamo and HDPlex DC-DC units.