You can just connect the gain control voltage lines from both the amplifiers together and feed the same control voltage into both. Make sure that the second amplifiers input will not be overloaded by the first amplifiers output. The voltage gain slope will be twice as steep when the amplifiers are in series.
Glad to help. Other companies making VGA chips would be Linear Tech and National but I think you'll find them around the same price range. On the prices of Analog Device parts; they have a fairlywide selection. Some are real specialized, like very low noise and distortion for ultrasound applications and hence expensive. But would something like two AD8324's in series work? They are fairly cheap.