Yes, it does. I was able to consolidate CO miles from a few different accounts into a single Amtrak account. I'm not sure if you're supposed to be able to do that, but they don't check the name on the destination Amtrak account, so it works.

Similarly, I would imagine it doesn't matter transferring out of Amtrak either, because they only ask for your United/Continental FF number, not the name on the destination account.

Also keep in mind that Amtrak doesn't check traveler names against Guest Rewards accounts like the airlines do, so sometimes it may make more sense to just use one Amtrak account for yourself and spouse, or the whole family, etc.