Technically, yes, but Amazon customers probably wouldn't benefit from that. I don't currently distribute or sell books directly because that creates a tax burden. So it's probably best to let the various stores handle it. I still want to sell books but I don't want my readers to be restricted by DRM for a book they paid for. The honor system is fine for me.

Edit: I now realize you might mean in the Amazon KDP UI. I don't see a way to upload your own.