Obviously *I* can't imagine why you'd want a dual SIM phone in Qatar ;-) though they're great for going on holiday (local SIM + home SIM).

My personal advice, based on experience, would be to stick with the Samsung models, which are purpose built and work well. Many others are retro-fitted with an accessory that's both messy and not entirely reliable. (I had a Nokia thing a few years ago. Grrr!) Also, because they're retro-fitted, there's no support from the manufacturer.

I brought my (excellent) Samsung SGH-D890 to Qatar with me. As far as I know Carrefour sells at least one dual SIM Samsung model, but, no surprise, you won't find any in a Vodafone shop! ;-)