Bob,
After reading all these posts I need to weigh in.
The reason keyboard amps differ from other amps are the frequencies that the amp receives and delivers. Keyboards put out the full spectrum of sound frequencies but if you don't care or need to hear them all then by all means get whatever you want. But if sound is really important to you think about it!
As for needing two amps, look at it this way. Most keyboards output sound in stereo, at least the keyboards with built-in speakers, with the idea that you're facing the middle of the instrument so stereo is used to put the sound in the middle. So to take advantage of this you could either use one amp with two channels to plug separately into or two amps, one for each side.
On stage I use two keyboard amps, one amp for each side eight feet apart, but that's for the bounce effect. (Bouncing sound from right to left, ect).
What your decision comes downs to is taste and need...