After you toggle the "CompStn" button on, the NSHARP Skew-T and hodograph display compares all active stations at the current time for the current source. The name of the station in the station table is color coded to match the colors of the Skew-T and hodograph traces.
The left/right arrow keys step through time. The up/down arrow keys cycle through stations. The shift + up/down arrow keys cycle through sources.
00z KDDC (red), and KAMA (green), and KABQ (purple) soundings and hodographs.
Toggling the filtering off using shift + left click for some stations in the inventory table on the upper right part of the display can help manage large numbers of soundings in compare mode.