Is this a thing you can do? I did a search and it seemed to be up for debate in the threads I found. I just dug out my book and this is what I found:
Creating magic double-headed weapons is treated as creating two weapons when determining cost, time, and special abilities.
That last bit about special abilities makes me lean towards the answer being yes, but I'd like some additional input.
Yes it is. Each end is enchanted separately. Note that both ends are MW for 600, though; you can't make just one end MW.
For magical purposes a double weapon are two distinct magical weapons who are just coincidentally glued together. They dont influence each other in any way whatsoever.
Alright, that's good to know. I was looking at a monk using double-chained kama, but since Monks can flurry with just one side (as I understand it) I figured I could save money on enchanting costs by only really enchanting one side and maybe throwing a situational enchantment on the off hand later on.